The National Building Museum has had an extra tenant for almost a year now, but they don’t seem to mind. Popular demand is what’s keeping the “LEGO® Architecture: Towering Ambition” exhibition around D.C. until Sept. 3, 2012, according to the museum’s executive director, Chase W. Rynd.

It can’t hurt that “one of the most-visited exhibitions in the Museum’s 31-year history” will stay at a time when the museum is struggling economically. Just three weeks ago, the National Building Museum announced it would join the ranks of other private museums in the District that charge admission. The LEGO show has had its own admission fee since it opened last summer, so the museum doesn’t have to worry about deterring visitors by asking for their cash—-well, at least until Sept. 4, 2012.

Parts of the Museum are still free to enter (like the gift shop!), while the exhibits cost $5-8, unless you’re a museum member or in the armed forces.