The site of President Abraham Lincoln's assassination on April 14th, 1865, Ford's Theater in Penn Quarter is today a working theater offering plays, musicals, and educational presentations in addition to maintaining a museum dedicated to Lincoln. The structure has been painstakingly restored, and serves as an example of Civil War-era Washington architecture. Be sure to pop across the street to the Peterson House, a boarding house where Lincoln died which has also become a museum.  Tickets are free but the lines can be long;  there is an option to reserve tickets in advance online for a small fee. Closed holidays.