Newgate

perhaps the most notorious London prison; originally built in the twelfth-century, the Victorian building dated from its reconstruction after the Gordon riots of 1780; it was situated at the north end of Old Bailey, near the central criminal court, until its demolition in 1902

note that the visit of Pinnie and Hyacinth to the dying Florentine Vivier in chapter 3 is not to Newgate, but to Millbank prison beside the Thames