Tower Hill Tunnel (London)

 tunnel, abandoned / shut down, invisible

The Tower Subway is a tunnel beneath the River Thames in central London, close — as the name suggests — to the Tower of London. Its alignment runs between Tower Hill on the north side of the river and Vine Lane (off Tooley Street) to the south. Its innovative method of construction provided the template for the construction in 1890 of the City & South London Railway, the first of London's "Tube" railways.

The tunnel is called a subway according to normal British usage, indicating a tunnel for pedestrians, and not to the American English usage, equivalent to underground rapid transit.

It is sometimes cited as world's first underground tube railway, though not the first underground railway. However, since it operated over a very short distance using a single car moved by a stationary engine, it may be more accurate to call it a horizontal lift.