However, it is one of the most unusual aspects of the Elizabeth Tower. 114 steps up inside the tower is the Prison Room, but you don't need to worry about being locked up there yourself. The prison room was used for MPs who breached codes of conduct, but it hasn't been used since 1880.

While "Big Ben" refers to the Great Bell, the Elizabeth Tower that houses it does contain several "hidden" or lesser-known rooms. The most famous "secret" is the Prison Room, located 114 steps up the tower. Historically, this room was used to imprison Members of Parliament who breached the code of conduct; the last person held there was Charles Bradlaugh in 1880. Another significant space is the Mechanism Room, which houses the Great Clock's massive gears and weights. Following the extensive renovations completed in recent years, the tower also features a newly installed elevator (lift) for accessibility, which required careful integration into the historic ventilation shafts. There is also the Ayrton Light room at the very top, which contains a lantern that shines when Parliament is in session after dark. While these aren't "secret" in the sense of being undiscovered, they are off-limits to the general public during standard tours, which typically focus on the clock dials and the belfry. In 2026, virtual tours now allow people to explore these restricted levels in high-definition 3D for the first time.