It's had all sorts of challenges over time. The Circle and District are just under the surface nearby, the Jubilee line is deep but still affected the foundations. The building across the road was demolished down to about six levels below ground level. The buildings it is attached (including Parliament and a school) to are up to 1000 years old and need to be vacated for major works from every type of damage, including WWII bombings. Also it's on the edge of what was once an island, and there's an underwater river nearby.