The Guildhall Art Gallery, London
This painting, by American-born John Singleton Copley, of the Great Siege of Gibraltar was commissioned by the City of London in 1783 and at over 458 square feet is one of Britain's largest oil paintings.
The painting depicts the Governor, General George Augustus Eliott, riding to the edge of the battlements to direct the rescue, by the British, of the defeated Spanish sailors. General Eliott was later created Lord Heathfield in 1787.
Another view of the Art Gallery showing some of the multiple levels. In the left foreground is the viewing gallery for the very large painting shown above.
Entry to the Guildhall Art Gallery is free at the time of writing (2012).
In the basement are the preserved remains of the Londinium Roman Amphitheatre. The pattern of green rectangles at the far end represents bench seating in the amphitheatre proper. This viewpoint is from the eastern entrance.
It was long suspected that Londinium must have had an amphitheatre but it wasn't until 1988 that these remains were discovered during excavations prior to building the new Guildhall Art Gallery.
Excavations of the remains continued until 1996 when it was declared an Ancient Monument and the designs for the Art Gallery had to be revised to preserve the remains in situ.