Elizabeth Tower, the clock tower called Big Ben, stands at the Palace of Westminster. You climb it twice: once as Evie repairing telegraph lines in Freedom of the Press, and once to deal with a Templar bomb at the top.
In Freedom of the Press, Evie rope-launches up Big Ben and crosses the Parliament rooftops, fitting new fuses to the telegraph line. Later that year, Boston Templars plant explosives across the palace, including one at the top of the tower, and one twin climbs up to stop it.
Bell has just turned a broken grappling launcher taken from Rexford Kaylock into the rope launcher on the twins' gauntlets. In return, Evie fixes the fuses atop the tower for the Free Press Association line Bell is building to rival the Starrick Telegraph Company, which makes this climb your first real test of the new tool.
Palace of Westminster
The Palace of Westminster, home of Parliament, is in Westminster beside the Clock Tower. It has a viewpoint, Jacob assassinates the Earl of Cardigan here in Motion to Impeach, and the twins later stop a Templar bomb plot inside.
10 Downing Street
10 Downing Street is the Prime Minister's home and office in Westminster. In 1868 Benjamin Disraeli lives here, and Jacob's work as his bodyguard in Sequence 7 starts outside the house.
Admiralty
The Admiralty is a government office on Whitehall in Westminster, one of the period buildings you can climb and read about in the in-game database. No memory centres on it.
Banqueting Hall
The Banqueting Hall, later the Chapel Royal, is a 1622 hall on Whitehall in Westminster and a database landmark in Syndicate. It is the only surviving part of the old Palace of Whitehall.