The Palombaro Lungo is the largest water reservoir of the city of Matera, dug under the central Piazza Vittorio Veneto, and part with the rock church of Santo Spirito complex of Hypogeum Piazza Vittorio Veneto. The tank extends below the square to the palace of the Annunciation, formerly the seat of the convent, and in the past it served as a water supply source for all the constructions placed "on the floor" (ie just outside the Sassi) near Piazza Vittorio Veneto. In addition to rainwater, in Palombaro Lungo it was also collecting water from a natural source located on Castle Hill Tramontano, that Lapillo's hill. The construction of the cistern dating back to the nineteenth century, and it was rediscovered only in the 1991 thanks to some scholars (led by Enzo Matera Screws, Video below, expert on underground Matera) that, during the first exploration, the they crossed aboard a raft.