Five Hundred Metres of Galleries beneath Ocaña Curiosity · Ocaña, Mesa de Ocaña, Toledo Image of Ocaña, not of the place itself. The Fuente Grande system conceals more than half a kilometre of underground galleries for collecting and channelling water, a 16th-century feat of engineering that still astonishes visitors. Photo: Speedyglides (CC BY-SA 3.0) What to see and do in Ocaña