Twice a year the Main Reading room is open to the public and photography is allowed. NO Tripods are allowed but there are plenty of places to set your camera on to get some really good shots. If you've never been there you need to check it out. One of the most beautiful places in DC. This will not be hosted so just come whenever you can during the Open House hours. From the LOC website:
February 17, 2014, 8:30 a.m. - 4:30 p.m.
The Jefferson Building s Great Hall and exhibitions will be open to the public, including a Main Reading Room Open House from 10 a.m. - 3 p.m. The Young Readers Center celebrates past and future presidents with hands-on activities like speech reenactments, trivia, crafts and more at 10 a.m. in Room G-29. All other reading rooms and other Library buildings will be closed in observance of the Presidents Day federal holiday.
Location: All buildings