Artificial caves of Alapraia, Archaeological burial site in Estoril, Portugal

The Artificial caves of Alapraia are four hypogea cut into marlstone with stone tools, each built as a low corridor ending in a circular chamber roofed by a skylight closed with slabs. Cave 1, the largest, has a 6.2 m chamber 2.8 m high and a 19 m passage; Caves 2 to 4 measure 4.2 to 6.2 m across.

The geologist Francisco de Paula Oliveira first described Cave 1 in 1889, when it was used as a wood store and animal shelter. Eugénio Jalhay and Afonso do Paço excavated Caves 2 and 3 in 1932 and 1942, and Cave 4 was found in 1943 during work to install a fountain. The site was classified as an Immovable of Public Interest in 1945.

These caves show how people from the Late Neolithic period buried their dead, arranging bodies along chamber walls with ritual objects placed nearby. The burial layout tells us about the spiritual beliefs and social organization of those ancient communities.

The four caves stand in the middle of Alapraia, surrounded by and partly beneath modern houses, and are marked on site but closed to casual visitors. Cave 1 lies behind a high wall. The finds are displayed in the archaeology room of the Condes de Castro Guimarães Museum in Cascais, inaugurated in 1942, and some pieces are shown at the Museu da Vila.

The special central openings earned these caves the name coelheira-type, as they provided alternative entry points when the corridors became blocked. This clever design by prehistoric builders ensured the burial chambers remained accessible even under challenging conditions.