Mosteiro de São Bento

High above the port of Rio de Janeiro, this hill has guarded Guanabara Bay since the final years of the sixteenth century. When the Benedictine monks arrived here in 1590, thanks to a land grant from a settler named Manoel de Brito, they were not just seeking a quiet retreat for prayer. They were claiming prime strategic ground in a young, vulnerable colonial outpost.

The building outside does not try to charm you. It was designed in 1617 by a royal military engineer named Francisco de Frias da Mesquita, and his priorities were unmistakably practical. Instead of dramatic flourishes, he delivered thick masonry, whitewashed walls, twin square towers capped with pyramids, and a clean triangular pediment. In Portuguese architecture, this no-nonsense approach is known as the estilo chão, the plain style. It looks less like an invitation to mystical contemplation and more like a citadel built to withstand a siege.

That defensive posture turned out to be entirely necessary. In September 1711, French privateer René Duguay-Trouin sailed into the bay with a squadron of warships, seized the city, and opened fire. Cannonballs rained onto this promontory, and the monks did not simply hide behind their stones. They actively joined the defense of the hill, helping man the perimeter while French shells battered the slopes.

Successive coats of plaster have smoothed over the battle scars over the centuries. But the stark military silhouette remains intact, guarding the secret waiting just beyond those front gates.