The Holocaust Museum houses 5000 artifacts in permanent exhibit, 20,000 more rotating with a separate exhibit geared to children. The most disturbing materials are behind walls and well marked for those who wish to avoid viewing. There is also a theater showing interviews with witnesses. Entrance to the museum is free, but timed tickets are required to view the Permanent Exhibition between March and August. These can be obtained at the Museum on the day of your visit or in advance by calling 202-488-0400 . Each day, the Museum distributes on a first-come first-served basis a large but limited number of timed entry passes for use that day. Access by public transportation: Take the MARC train from Penn Station to Union Station then take the Metro to the Smithsonian station or drive to one of the Metro stations, park and take the Metro to the Smithsonian station. Take Independence Ave. then walk two blocks west to Rauol Wallenberg Place, S.W.