What is the official designation of the building visible from the Morpeth Arms in a manner enabling spying?
Morpeth Arms: The Morpeth Arms is a public house at 58 Millbank, in the Pimlico district of London. Morpeth Arms:  It now contains a Spying Room which provides a good view of the headquarters of the Secret Intelligence Service across the river. SIS Building: The SIS Building or MI6 Building at Vauxhall Cross houses the headquarters of the Secret Intelligence Service (SIS, MI6), the United Kingdom's foreign intelligence agency.
SIS Building or MI6 Building