[Moonliner]

Originally Posted by JWBear

Source?

For starters the same Wiki article you mentioned.

National House of Prayer

Congress has designated the Washington National Cathedral as the "National House of Prayer". During World War II, monthly services were held there "on behalf of a united people in a time of emergency". Before and since, the building has hosted other major events, both religious and secular, that have drawn the attention of the American people.