The Park Tunnel is one of Nottingham's better-kept oddities: a high, arched passage cut 350 feet through solid sandstone in the 1850s, intended as a carriage road between the genteel Park Estate and Derby Road, but rendered useless by an engineering miscalculation before it even opened.
Today it's a pedestrian shortcut — eerily quiet, lit by skylights cut into the rock above, and a useful way of getting between the Park Estate's wedding-cake Victorian villas and the city centre. The Park Estate itself, a private residential enclave still lit by gas lamps, is the largest such estate in Europe and worth a wander in its own right.