- Jul 31, 1731
- Ben Franklin founds the Library Company
- 1731
- July 1: Benjamin Franklin and others found the Library Company of Philadelphia
- 1825
- Northwest Square renamed Logan Square for William Penn's secretary, James Logan
- 1833
- April 9: Citizens of Peterborough, New Hampshire found first free public library in the United States
- 1864
- SS. Peter and Paul Roman Catholic Cathedral by architects Napolean Le Brun and John Notman is completed
- June: The U.S. Sanitary Commission hosts the Great Central Fair at Logan Square to support Civil War troops
- 1868
- December 28: Architect Horace Trumbauer born in Philadelphia
- 1876
- American Library Association founded in Philadelphia
- Library Journal founded
- First edition of the Dewey Decimal Classification System published
- 1881
- April 30: Architect Julian Abele born in Philadelphia
- 1883
- Horace Trumbauer enters architecture profession as an errand boy in the office of G. W. and W. D. Hewitt
- 1884
- April 29: New Jersey real estate developer Charles K. Landis issues a plan for a boulevard from City Hall to the entrance to Fairmount Park, later dubbed the Fairmount Parkway
- 1887
- The Commonwealth of Pennsylvania authorizes the creation and regulation of municipal libraries
- Nov 30, 1889
- Pepper bequest founds the Free Library of Philadelphia
- 1889
- November 30: George S. Pepper executes his last will and testament that includes a bequest to found the Free Library of Philadelphia
- 1890
- Free Library benefactor George S. Pepper dies
- Horace Trumbauer leaves the Hewitts' architectural firm and opens his own firm at 310 Chestnut Street
- 1891
- The court grants a charter for the Free Library of Philadelphia
- December 21: Mayor Edwin S. Stuart signs an ordinance appropriating $15,000 to the Board of Education to establish the Philadelphia Public Library
- 1892
- April 12: Mayor Edwin S. Stuart signs an ordinance that places the Fairmount Parkway on the official city plan for the first time
- Mar 12, 1894
- First Central Library opens in City Hall
- 1894
- March 12: First Central Library opens in City Hall
- December 31: Mayor Stuart signs two ordinances consolidating the Philadelphia Public Library into the Free Library and establishing the Free Library's Board of Trustees
- 1895
- February 11: The Central Library moves to 1217-1221 Chestnut Street
- June 7: The Commonwealth of Pennsylvania authorizes Philadelphia to levy taxes and make appropriations for the establishment and maintenance of public libraries
- November 11: Mayor Charles F. Warwick signs ordinance for the maintenance and enlargement of the Free Library of Philadelphia
- 1896
- July 16: Mayor Charles F. Warwick authorizes a first referendum on borrowing $1 million for a central library site and building; it fails
- 1897
- May 14: The Free Library's Board of Trustees forms committee to select a suitable site for a central library building
- September 27: Mayor Charles F. Warwick authorizes a second referendum on a loan that includes $1 million for a central library site and building; it succeeds
- Nov 2, 1897
- Philadelphia voters approve a referendum for a new central library building
- November 2: Philadelphia voters approve a referendum for a new central library building
- Horace Trumbauer begins the design of Lynnewood Hall, library trustee Peter A. B. Widener's mansion in Elkins Park
- 1898
- Free Library founder Dr. William S. Pepper dies
- June 17: Mayor Charles F. Warwick signs an ordinance creating a loan that includes "one million (1,000,000) dollars for library site and building: PROVIDED, Not more than one million (1,000,000) dollars shall be expended by the City in payment of site and erection of building"
- Peter A. B. Widener donates his mansion at Broad and Girard Streets for the Free Library's Josephine H. Widener Memorial Branch
- 1899
- October 27: Legal counsel informs Free Library officials that they cannot construct a library building on Logan Square
- 1900
- May 8: Free Library's Josephine H. Widener Memorial Branch opens after renovations by Horace Trumbauer
- November 9: Free Library officials consider the old United States Mint at Chestnut and Juniper Streets as a site for the new central library building
- 1902
- November 15: Free Library officials accept sealed proposals for a site for the new central library building
- November 28: Free Library officials reject all sealed proposals for sites for the new central library building
- Jun 18, 1902
- Julian Abele graduates from University of Pennsylvania
- June 18: Julian Abele is the first African American to graduate from the architecture program at the University of Pennsylvania
- March 25: The Philadelphia City Council awards first prize to New York architects Lord & Hewlett in a competition for a Soldiers and Sailors Monument for Logan Square
- 1903
- April 25: Horace Trumbauer marries Sara Thomson Williams
- March 20: The Commonwealth of Pennsylvania authorizes the Free Library to accept Andrew Carnegie's $1.5 million gift for the erection of 30 branch libraries
- April 17: Peter A. B. Widener suggests the City Hall end of the Fairmount Parkway as the site for the central library building
- 1904
- February: Architectural Record publishes a lengthy account of Horace Trumbauer's work
- 1906
- Abele joins Trumbauer's firm
- Julian Abele joins Horace Trumbauer's architecture firm
- January 12: Free Library officials consider School of Industrial Art building at Broad and Pine Streets as a site for the central library building
- October 13: Mayor John Weaver signs an ordinance authorizing the opening of the Fairmount Parkway west of Logan Square
- October 15: Free Library officials select a site for the central library on the north side of the Fairmount Parkway between Fifteenth and Sixteenth Streets
- November 30: Free Library officials select Horace Trumbauer to prepare preliminary plans for the central library on the Fairmount Parkway between Fifteenth and Sixteenth Streets
- 1907
- January: Horace Trumbauer completes the preliminary design for the central library on the Fairmount Parkway between Fifteenth and Sixteenth Streets
- Feb 22, 1907
- Construction begins on the Fairmont Parkway
- February 22: Construction begins on the Fairmount Parkway, renamed the Benjamin Franklin Parkway in 1937
- December 12: The Fairmount Park Art Association unveils a new design for the Fairmount Parkway by architects Horace Trumbauer, Clarence Zantzinger, and Paul Cret
- 1909
- June 8: The City authorizes the revision of the Fairmount Parkway to comply with a compromise version of the design prepared by Horace Trumbauer, Clarence Zantzinger, and Paul Cret for the Fairmount Park Art Association, freeing the plot for the central library
- October 7: Mayor John E. Reyburn founds the Comprehensive Planning Committee
- 1910
- January 21: Library officials first consider a site for the central library on the Fairmount Parkway at Logan Square between Nineteenth, Twentieth, Vine, and Wood Streets
- February 18: Library officials resolve to acquire the site for the central library on the Fairmount Parkway at Logan Square
- Dec 1, 1910
- The Central Library moves to the College of Physicians Building
- December 1: The Free Library's Central Library moves to the College of Physicians building at Thirteenth and Locust Streets
- December 29: Mayor John E. Reyburn signs an ordinance authorizing the City to borrow $1 million for the central library site and building from the 1898 loan
- Apr 8, 1911
- Mayor Reyburn sets aside Parkway plot for the library
- 1911
- April 8: Mayor John E. Reyburn signs an ordinance setting aside the central library plot on the Fairmount Parkway at Logan Square
- April 10: Traction magnate and library trustee Peter A. B. Widener suggests Horace Trumbauer as the Free Library's advisor for an architectural competition to find a design of the central library
- April 21: The Free Library Board of Trustees creates the Committee on Main Library Site and Building to erect the central library
- May 15: The First Municipal City Planning Exhibition in America opens at City Hall and includes a model of the Fairmount Parkway showing a library at Logan Square
- May 23: The New York Public Library by architects Carrère & Hastings opens; it serves as a model for the central library's design
- June 1: Mayor John E. Reyburn decides that the Free Library should not hold a design competition, but should appoint Horace Trumbauer as the architect of the central library
- Jun 7, 1911
- Preliminary floor plans are submitted for Central Library
- June 7: Assistant Librarian John Ashhurst 3rd and Horace Trumbauer's preliminary floor plans are submitted to the Committee on Main Library Site and Building
- June 10: Horace Trumbauer accepts his appointment as architect of the central library
- June 29: The Fairmount Park Commission selects Horace Trumbauer to collaborate with the firm of Zantzinger, Borie & Medary to design the Philadelphia Museum of Art
- July 5: Mayor John E. Reyburn signs ordinances appropriating $1 million for the central library from the 1898 loan and confirming the purchase of properties on the Fairmount Parkway at Logan Square for the central library
- September 1: Head Librarian John Thomson tells Horace Trumbauer that "We are all getting very anxious to see your suggested sketch and plans for the Main Library Building."
- October 5: Architect Julian Abele of the Trumbauer firm presents a colored sketch plan and various floor plans to the Committee on Main Library Site and Building
- October 6: After the plan for the central library is presented to the Free Library's Board of Trustees, Horace Trumbauer is instructed to proceed with working drawings
- December 2: Mayor John E. Reyburn signs an ordinance striking streets on the central library site from the official City Plan
- 1912
- February 14: Free Library Board of Trustees president Henry R. Edmunds and Head Librarian John Thomson present a petition to Mayor Rudolph Blankenburg advocating the completion of the Fairmount Parkway
- March 15: Mayor Rudolph Blankenburg is "very anxious that the Trustees of The Free Library should commence building operations."
- April 14: Free Library trustee Harry Elkins Widener and his father George D. Widener, the grandson and son of Free Library benefactor Peter A. B. Widener, die on the Titanic
- April 26: A committee of the City's Art Jury recommends approval of the preliminary plans for the central library
- April 29: Library officials release "a little book showing a good perspective view of the south and east facades of the building, and a ground plan, showing its proposed location, together with five floor plans of the building."
- June 7: Financial problems force the Free Library's Board of Trustees to consider constructing the central library in sections
- 1913
- February 13: Horace Trumbauer prepares a plan to construct the central library section by section
- March 29: Head Librarian John Thomson solicits a donation from Andrew Carnegie for the erection of the central library
- Apr 2, 1913
- Carnegie refuses to fund Central building
- April 2: Andrew Carnegie refuses to fund the erection of the central library
- May 24: City Solicitor Michael J. Ryan issues an opinion stating that the 1898 loan money cannot be used for the construction of the central library
- 1914
- September 24: Mayor Rudolph Blankenburg signs an ordinance to borrow $40,000 for the central library to overturn the 1898 loan restrictions
- November 5: Mayor Rudolph Blankenburg authorizes the erection of a temporary building for evangelist Billy Sunday on the central library site
- 1915
- January 7: Mayor Rudolph Blankenburg signs ordinances appropriating $40,000 for the central library and overturning the 1898 loan restrictions
- March 25: Mayor Rudolph Blankenburg requests that library officials restart the central library construction effort
- May 21: The Philadelphia City Council extends Logan Square west to Twentieth Street
- July 17: City Solicitor Michael J. Ryan authorizes commencement of construction of the central library following approval of the $40,000 loan
- August 13: Horace Trumbauer states that "The preliminary plans and studies are completed and preparation of the working drawings and specifications can be started immediately, requiring about ninety days for their completion."
- August 16: The Free Library's Board of Trustees authorizes Horace Trumbauer to proceed with plans and specifications and schedules the groundbreaking for September 16, 1915
- Aug 20, 1915
- Groundbreaking is cancelled and construction is postponed
- August 20: City Solicitor Michael J. Ryan issues a legal opinion stating that the City Council must approve the construction of the central library, forcing library officials to cancel the groundbreaking and postpone construction
- 1916
- January 20: The City signs a contract with Horace Trumbauer for the central library
- February: Head Librarian John Thomson dies; Assistant Librarian John Ashhurst 3rd appointed head of the Free Library
- February 18: Mayor Thomas B. Smith authorizes the Free Library to enter into a contract for the construction of the central library
- May 16: Philadelphia voters approve a loan referendum including $2.46 million for the central library and $9 million for the Fairmount Parkway
- December 29: The Art Jury approves the updated plans for the central library
- 1917
- March 19: The Mason Builders' Association threatens to block the construction of the central library if the stone is not cut in Philadelphia
- March 23: Indiana limestone interests file the first Walter R. Taylor vs. City lawsuit to block the construction of central library, withdrawn on March 29, 1917
- March 27: Bids opened for the construction of the central library
- April 2: Contracts awarded for building, plumbing, electrical, and heating and ventilation of the central library
- April 3: Local stone cutters file the John F. Flinn vs. City lawsuit to block construction of the central library
- April 10: The lower court refuses to grant a preliminary injunction blocking the construction of the central library in the John F. Flinn vs City lawsuit
- 1917 – 1918
- Landscape architect Jacques Gréber converts Logan Square into a circle
- May 12, 1917
- Ground broken for the Central Library
- May 12: Ground is broken for the central library
- May 22: On appeal of John F. Flinn vs. City, the Pennsylvania Supreme Court grants the injunction blocking the awarding of contracts for the construction of the central library; the construction contracts are annulled
- July 12: New bids are received for the central library building, plumbing, and electrical contracts
- July 17: New central library building, plumbing, and electrical contracts are awarded
- October 13: Court refuses to grant a preliminary injunction blocking the construction of the central library in the second Walter R. Taylor vs. City lawsuit
- 1918
- January 19: Horace Trumbauer completes detailed drawings for the central library
- January 30: Jacques Gréber's redesign of the Fairmount Parkway are exhibited publicly
- Oct 26, 1918
- Fairmount Parkway opens
- October 26: Fairmount Parkway officially declared open
- 1919
- June 16: Horace Trumbauer directed to provide steel frame in place of the masonry, load-bearing walls for the central library
- 1920
- February 25: Mayor J. Hampton Moore requests that the central library be redesigned to reduce cost
- March 30: Horace Trumbauer reduces the size of the central library from seven to six million cubic feet
- September 14: Bids are opened for the excavation and construction of the central library foundations, John Gill & Son's bid of $425,000 is the lowest; all bids are later rejected by the Department of Public Works as too high
- December 21: New bids are opened for the excavation and construction of the foundations; Standard Construction Company's bid of $268,750 is the lowest
- 1921
- Sculptor Hermon Atkins MacNeil and architects Lord & Hewlett erect a pair of stelae as the Soldiers and Sailors Memorial at Twentieth Street and the Fairmount Parkway
- February 14: The Standard Construction Company restarts construction of the central library foundations
- Nov 20, 1921
- Foundations of the Central Library completed
- November 20: The Standard Construction Company completes the foundations of the central library
- December 2: Horace Trumbauer signs a new contract based on the revised central library design
- 1922
- January 27: Horace Trumbauer completes new preliminary plans for the central library
- February 21: Bids are opened for the erection of the building; the P. H. Kelly Company's bid of $1,367,000 is the lowest
- March 1: The P. H. Kelly Construction Company is awarded the contract to erect the central library
- March 16: Horace Trumbauer begins new detailed drawings of the central library
- April 10: The P. H. Kelly Company begins construction of the central library
- April 24: The Art Jury recommends approval of the revised plans of the central library
- Jan 24, 1923
- Cornerstone laid for Central building
- 1923
- January 24: Mayor J. Hampton Moore led a ceremony to lay the cornerstone of the central library
- June 2: The P. H. Kelly Company completes the erection of central library's steel frame
- December 5: The contract for the central library's heating and ventilating systems is awarded to John H. Cooney for $397,500; contract for the plumbing and drainage systems to the W. G. Connell Company for $236,000
- 1924
- April 29: The contract for the central library's electrical system is awarded to the W. V. Pangborne & Company for $188,600
- July 24: The Swann Memorial Fountain by sculptor Alexander Stirling Calder and architect Wilson Eyre at the center of Logan Circle is switched on for the first time
- 1925
- June 6: Julian Abele marries Marguerite Bulle
- Feb 28, 1925
- The exterior building of Central Library is completed
- February 28: The exterior of central library is completed
- July 29: The contract for the interior of the central library is awarded to F. W. Mark Construction Company for a bid of $2,417,241
- 1926
- July 8: Horace Trumbauer completes the final revisions to the central library design
- October 30: The old Central Library at Thirteenth and Locust Streets closes
- 1927
- January 20: The first books are moved into the Central Library
- Jun 2, 1927
- Opening Day
- June 2: Dignitaries open the Central Library with a grand ceremony on the lawn across Vine Street from the building
- 1928
- March 16: The Art Jury approves Paul Cret and Jacques Gréber's design for the Rodin Museum
- March 27: The Philadelphia Museum of Art opens
- 1929
- April 24: The Saint George's Society dedicates a Shakespeare Memorial by sculptor Alexander Stirling Calder and architect Wilson Eyre across Vine Street from the Central Library entrance
- November 29: The Rodin Museum opens
- 1931
- May 11: The Art Jury approves John T. Windrim and W. Morton Keast's design for the Municipal Court building, the Central Library's twin
- 1932
- April 14: The Art Jury approves John T. Windrim's design for the Franklin Institute building
- 1934
- January 1: The Franklin Institute opens
- 1938
- September 17: Ground is broken for the Municipal Court building
- September 18: Horace Trumbauer dies
- 1939
- February 2: Samuel T. Freeman & Company auction house sells Horace Trumbauer's important collection of rare architecture books
- 1941
- January 22: The Municipal Court building opens
- 1950
- April 23: Julian Abele dies