The place already had a name before the Portuguese gave it one. The Tupinambá and Pacajá who lived along the Guamá called it Mairi, and the people of the surrounding villages answered to the cacique Guaimiaba. They fished the bay, moved through forests that flooded and drained with the tide, and had done so for generations before a stockade appeared on the bluff. What followed was not a peaceful handover. The conquest of Pará was carried out through warfare, enslavement and epidemic disease, and the Indigenous population of the lower Amazon was shattered by it. The colonial grid that survives here was laid over somebody else's landscape, and the tides that still time the day in Cidade Velha are the same tides the Tupinambá read.

Wood gave way to stone, and the Presépio became the Forte do Castelo, a masonry work looking straight down the water where enemy sail would have appeared. Its original cannons are still mounted. Inside, the collection is older than anything Portugal built here: Marajoara and Tapajônica ceramics, painted vessels and burial urns made by cultures that flourished on Marajó Island and the Tapajós River centuries before European contact. The fort now anchors the Feliz Lusitânia complex, the restored cluster of colonial buildings that gave the settlement its first, short-lived name — Fortunate Lusitania — and it remains the single best place to understand why the city sits where it does.

A short walk uphill stands the cathedral, Nossa Senhora da Graça, completed in 1771 and known simply as the Sé. Its design owes much to Antônio José Landi, born Giuseppe Antonio Landi in Bologna, who came to the Amazon with a technical commission in 1753 and never left, spending nearly forty years redrawing the city's churches and streets. The interior is deliberately overwhelming for a building at the edge of the rainforest: ten side altars, a wall of paintings, twenty-eight bronze chandeliers made in England, and a main altar donated by Pope Pius XI. Nearby, the Church of Saint Alexander — its present building finished in 1719 in a heavy Amazonian baroque — holds the most important Jesuit complex in Brazil, restored to house the Museum of Sacred Art.

Read the street signs and you get a map of somewhere else. Avenida Portugal. Rua de Aveiro. Rua de Óbidos, Rua de Breves, Avenida Almirante Tamandaré, Rua Ângelo Custódio — which locals long called the Rua Longa, the Long Street, and which was laid out in the 1600s. The third street the Portuguese cut was named for its horsemen, Rua dos Cavaleiros, before being renamed for a physician-governor. Taken together with the adjoining quarter, the historic centre gathers roughly 2,800 buildings protected as national heritage by IPHAN: townhouses with shops on the ground floor, warehouses, chapels, palaces. Almost nowhere else in Brazil holds this much colonial fabric on this scale.

The neighborhood you walk through today is only partly colonial. Between roughly 1880 and 1912, rubber money washed over Belém, and the old quarter was refaced in it — European façades, imported ironwork, and above all azulejo, the glazed Portuguese tile that sheathes entire buildings here and still throws back the afternoon light. The Solar Barão de Guajará, finished in 1873, is tiled from pavement to roofline. Casa Rosada, built in 1760 on Rua Siqueira Mendes for a captain-engineer who helped prepare the region's defences against a feared French attack in 1795, sits a few doors from mansions raised a century later on latex. When the boom collapsed, the money left and the surfaces stayed. That is the particular character of Cidade Velha: a fortified colonial village wearing the clothes of a brief and spectacular fortune.