Built alongside the Palace is the Clock Tower, home to Big Ben.
During the Renaissance, it housed a secret court known as the Star Chamber, named for the stars painted on the ceiling of the meeting room. There, members could try powerful members of society whom ordinary courts were incapable of convicting. King Henry VII offered the Italian Assassins a seat in the Chamber after they killed his enemy Margaret of York.
In 1868, the Earl of Cardigan, a Conservative politician, veteran of the Crimean War, and Templar, was killed inside the palace by the Assassin Jacob Frye. Later that year, following the death of Crawford Starrick, Templars based in Boston, US attempted to blow up the Palace, but were thwarted by the Assassins, operating on behalf of the Order of the Sacred Garter.
- Shaun Hastings used the pseudonym "Guy Fawkes" for his online activities; Fawkes plotted to assassinate King James I by blowing up the Palace during the Gunpowder Plot in 1605.