Fort of Nossa Senhora das Mercês de Catalazete

The Fort of Nossa Senhora das Mercês de Catalazete (Forte de Nossa Senhora das Mercês de Catalazete) is a small 18th-century coastal battery on the northern bank of the Tagus estuary, in the municipality of Oeiras, Lisbon District. It is also called the Fort of Catalazete, the Catalazete Battery or Forte Novo das Mercês. It stands near Paço de Arcos, on a stretch of coast that defended Portugal's capital from the sea for centuries.

When and why was it built?

The fort dates to 1762. A small battery was raised on a site between the Fort of São Julião da Barra and the Fort of Santo Amaro do Areeiro, with the aim of strengthening the defence those two larger forts provided. It began as a simple masonry structure, and work was completed in 1763.

What were its guns and garrison?

The battery was armed with nine pieces: two bronze cannons of 40-calibre and seven iron cannons of 24-calibre. Captain Sebastião Pereira de Mesquita commanded the garrison. It was meant as a supplement to the wider defensive system rather than a stand-alone stronghold.

What happened to it later?

After the wars linked to the Seven Years' War ended, the fort was left without a military garrison. By 1777 it still held ten pieces of artillery, but its care had been entrusted to a civilian family who were to keep and preserve it. The structure nevertheless fell into ruin, and repairs were carried out in 1793.

A violent storm on 15 February 1941 did serious damage, causing part of the already ruined right flank to collapse.

A new life after 1955

From 1955, restoration works adapted the site as a holiday colony for young people. On 20 April 1977 it was handed over to the Portuguese Youth Hostel Association.

Why does it matter?

The Catalazete fort shows how a small mid-18th-century battery fitted into the defences of the Tagus estuary. If you are exploring Lisbon's western suburbs and are interested in coastal fortifications, it pairs naturally with its neighbours, the Fort of São Julião da Barra and the Fort of Santo Amaro do Areeiro.

Frequently asked questions

Where is the fort? On the right (northern) bank of the Tagus estuary, in the municipality of Oeiras, near Paço de Arcos.

When was it built? The battery was raised in 1762 and completed in 1763.

Why was it built? To strengthen the defence provided by the forts of São Julião da Barra and Santo Amaro do Areeiro.

Was it damaged? Yes. A storm in 1941 collapsed part of the right flank, and restoration began in 1955.

What was it used for after adaptation? First as a youth holiday colony, and from 1977 it was handed over to the youth hostel association.

Check current access conditions before visiting, as visiting rules may change.