| 1790 | Congress passes the "Residence Act," which provides that the federal government will be located in a permanent site on the Potomac River by 1800. |
| 1791 | Pierre Charles L'Enfant develops plan for capital city; he and President Washington select site for "Congress House." |
| 1792 | L'Enfant dismissed. Competition announced for design for Capitol; Dr. William Thornton submits design after deadline. |
| 1793 | On recommendation of President Washington, Thornton awarded first prize in competition. Washington lays cornerstone. |
| 1800 | Congress moves from Philadelphia. Only the north wing of the Capitol is complete. |
| 1801 | Supreme Court first meets in Capitol. |
| 1803 | President Jefferson appoints Benjamin Henry Latrobe to continue work on building. |
| 1807 | South wing occupied by House. |
| 1808 | Latrobe begins rebuilding north wing. |
| 1810 | Senate occupies chamber in north wing; room below constructed for Supreme Court. |
| 1814 | Capitol burned by British troops. |
| 1815-1817 | Latrobe rehired to restore the Capitol. He resigns over disputes about authority. |
| 1818 | Charles Bulfinch appointed by President Monroe to succeed Latrobe. Center building begun. |
| 1819 | Supreme Court, Senate, and House meet in reconstructed rooms in the Capitol. |
| 1824 | Rotunda first used for Lafayette's reception. |
| 1829 | Building completed, including west terraces and landscaping. |
| 1850 | Competition held for design to extend Capitol; five architects split prize. |
| 1851 | President Fillmore appoints Thomas U. Walter as "Architect of the Capitol Extensions"; cornerstone laid. Library of Congress (then located in the Capitol) destroyed by fire. |
| 1855 | Congress votes to replace Bulfinch's wooden/copper dome with cast-iron dome designed by Walter; Constantino Brumidi paints first fresco in the Capitol. |
| 1857 | House holds first session in new hall. |
| 1859 | Senate holds first session in new chamber. |
| 1860 | Old Senate Chamber converted into Supreme Court Room. |
| 1861 | Work on extensions suspended for 11-1/2 months because of Civil War; Capitol used during that time as Union hospital, barracks, and bakery. Work on dome continues. |
| 1863 | Statue of Freedom raised into place atop dome. |
| 1864 | Old Hall of Representatives designated National Statuary Hall. |
| 1866 | Scaffolding removed from beneath Brumidi's Apotheosis of Washington. |
| 1870 | Exteriors of extensions completed. |
| 1874 | Congress places Frederick Law Olmsted in charge of planning Capitol Grounds. |
| 1884-1892 | Olmsted terrace constructed. |
| 1885 | Experimental installation of electric lighting in Senate cloak room, lobby, and stairways. |
| 1890-1900 | Electric lighting installed throughout building and grounds. |
| 1894 | Completion of modern plumbing throughout building. |
| 1897 | Library of Congress moves to its first building (later named the Thomas Jefferson Building). |
| 1902 | Roofs of old House and Senate wings reconstructed and fireproofed. |
| 1935 | Supreme Court moves into its own building. |
| 1949-1951 | House and Senate chambers redesigned and remodeled. |
| 1958-1962 | New marble east front constructed 32-1/2 feet east of old sandstone front. |
| 1975-1976 | Old Senate Chamber and Old Supreme Court Chamber restored; partial restoration of National Statuary Hall. |
| 1983-1987 | Restoration of west front. |
| 1991-1993 | West terrace restoration/infill project. |
| 1993 | Restoration of the Statue of Freedom. |
| 2000-2008 | Construction of the Capitol Visitor Center |
