They are situated in the centre of the suburb of Alapraia in Estoril, Lisbon District, Portugal and are believed to date back to the last quarter of the 4th Millennium BCE and to have been used as a necropolis for over one thousand years.

All the caves had the same system of construction, consisting of a long corridor or vestibule for access, with a circular chamber at the end with a skylight at the top, protected by slabs.

This is believed to have made possible the placement of bodies into the chamber, when occupancy levels no longer allowed access through the corridor.

Items found included decorated ceramic vessels, such as bowls and cups, shale plates with a geometric pattern, polished bone items, flints, pearls, votive idols, and limestone replicas of two soles of sandals, which are believed to be unique.

The finds are mainly located in the Condes de Castro Guimarães Museum in neighbouring Cascais, where an archaeology room was inaugurated to display them in 1942.