St Marys. This largely forgotten station opened on the East London Line in 1884, although it switched over to the Metropolitan Line a few months later, and was situated on Whitechapel Rd, later famous for being the second cheapest property in Monopoly. It was always a tiny, cramped station and the move of Aldgate East to within 100m meant that St Marys was redundant, and it closed in 1938.
Built/ never used Underground Station. In 1903, operators dug tunnels for a station called North End/ Bull & Bush. The station was whittled out of the subsurface rock, ready for tiling and the final touches that make an Underground station useable. It was an engineering marvel, the deepest station below the surface on the Underground network, except it was never completed b/c potential passengers were judged too low to risk the investment of finishing.