London’s underbelly is equally fascinating. Underground tunnels and forgotten passageways lurk beneath the streets, remnants of the city's long and complex history. The Clerkenwell House of Detention, once a notorious Victorian prison, is a haunting part of London's past, still preserved in fragments beneath the city. Similarly, the London Stone, which dates back to Roman times, still sits, often unnoticed, in a niche on Cannon Street. This seemingly unremarkable stone was once believed to be the heart of the city, and many historical events have revolved around it, but few know of its significance today.