The Saturn V Dynamic Test Stand or Dynamic Structural Test Facility is a 360 foot high building at NASA Marshall Space Flight Center, Huntsville, AL inside which the fully-stacked Apollo Saturn V rocket was subjected to various structural loading and vibration tests in the 1960s. The building was later modified to support the same testing for the fully-stacked STS Space Shuttle system.
Read more in the National Register of Historic Places listing for the location.
For the technically inclined...