Gruta do Poço Velho

Gruta do Poço Velho is a prehistoric cave complex in the very heart of Cascais, a few steps from the Visconde da Luz garden and behind the São José building. Listed as a cultural heritage monument of Portugal, it is one of the most intriguing archaeological stops on the coast west of Lisbon, and it sits right beside ordinary town streets.

What is Gruta do Poço Velho?

It is a network of underground passages cut into limestone, forming a single cavern with several entrances and branching corridors. It took shape over thousands of years as an underground watercourse slowly eroded the rock and carved winding galleries. The plural name, Grutas do Poço Velho, refers to the whole system of chambers and passages.

Why does it matter to archaeologists?

Research here has uncovered traces of human presence from the Paleolithic through to Late Antiquity. The heaviest use falls in the Neolithic and Chalcolithic, the fourth and third millennia BC, when the cave served as a necropolis. More than a hundred burials have been identified inside.

The cave was documented in the 19th century by Carlos Ribeiro, a Portuguese engineer and researcher. He excavated here in 1879 and collected a considerable number of artifacts, which still help reconstruct life around Cascais in prehistory.

How to visit

For years the cave was closed to the public, but the municipality has opened it for visits. Entry is free and the visit takes about 10 minutes, so it fits easily into a walk through the old town. You can explore on your own during set hours on weekends and public holidays, or book a guided visit. Opening hours change with the season, so check the Cascais municipality website before you go.

Practical notes

• Location: central Cascais, beside the Visconde da Luz garden, behind the São José building.
• Visit length: about 10 minutes.
• Admission: free.
• This is a natural cave, so wear sturdy shoes and watch for damp, uneven ground.

Frequently asked questions

Is Gruta do Poço Velho free to enter? Yes, the visit is free.

How long does a visit take? About 10 minutes, which makes it a handy stop between other Cascais sights.

Can I join a guided tour? Yes. Besides self-guided visits, you can book a guided one.

How old are the finds? Traces reach from the Paleolithic to Late Antiquity, but the main period of use was the Neolithic and Chalcolithic, when the cave was a burial site.

Who first studied the cave? Carlos Ribeiro, a Portuguese engineer and researcher, who excavated it in 1879.

Is it suitable for families? Yes, the short visit and central location make it easy to combine with a stroll through Cascais, though the interior is uneven and calls for care.