The Grand Staircase at Knossos Palace

The Knossos Palace remains are sited just south of modern day Heraklion in Crete. It was the centre of the Minoan civilisation and in mythology was the residence of King Minos. It is noted for its use of luxury materials, complex 'labyrinthine' architectural plan, advanced building techniques (including measures against earthquake damage and drainage that still works) and impressive size. These are remains of the second palace on the site, which lasted from about 1700 to 1350 BCE.
The Grand Staircase is in the east wing of the Palace. It was once thought to have led down stairs to the royal apartments, but recent opinion holds that the rooms below would have been too gloomy for royal occupation. There are 54 stairs, remarkably well preserved.