You're standing at the old Sintra town jail, now the local post office.
Last reviewed 4 September 2026 · A two-minute read · 2835 BC–1979
The short answer
Praça da República in Sintra holds the former Cadeia da Vila de Sintra, the town's jail from 1822 until 1911, when architect A. Marques da Silva converted it into a post, telegraph and telephone station. It once shared a wall with the adjoining clock tower and held men suspected in a 1908 plot against the king.
Cadeia da Vila de Sintra, Praça da Republica, Sintra, 2010 — 2010 · DimiTalen · CC0
1822 to 1911
The town jail became a post office
You're standing at the Cadeia da Vila de Sintra, a building that spent most of its life as a jail and is now Sintra's post office. Beside it stands the old clock tower, the 33 meters, once physically joined to the prison next door.
In 1822, builder Pedro d'Oliveira rebuilt the old prison tower and added a new jail building onto it. For decades the two structures shared one wall. That connection became a problem. On 4 October 1852, the town chamber ordered the passage between the tower and the prison sealed shut, worried that prisoners were using it to escape.
By the 1890s, officials decided the old jail was no place to keep anyone. It lacked basic conditions for the people locked inside.
In 1906, architect Arnaldo Redondo Adães Bermudes drew up plans for a replacement, the Cadeia Comarcã, built on the grounds of the old São Sebastião Cemetery. Workers broke ground on 21 November that year. Bermudes later became a republican senator.
The new prison opened on 13 June 1909, timed to the Primavera de Sintra festival, the same day the town hall opened too. Its layout was unusual: a hexagonal building with cells arranged around a central courtyard, where prisoners worked by day under guard.
The old jail didn't stay empty long. After men involved in a failed plot to kill the king were rounded up in January 1908, some were held in this older building. Writers passed through its cells too. Novelist Camilo Castelo Branco was imprisoned here at some point in the 1800s, and wrote while locked inside.
By 1911, the old prison's working life as a jail was over. Architect A. Marques da Silva converted the building into a station for mail, telegraph and telephone service.
1908 and after
The hexagonal prison that replaced this jail
The new Cadeia Comarcã, the hexagonal prison that replaced this building, carried its own strange history forward. The men swept up after the failed attempt to kill the king in January 1908 had already passed through the old jail's cells before the new one even opened. One source, told as local report rather than settled fact, describes a riot inside the Comarcã sometime in the twentieth century, with guards stationed at the rear entrance firing through the window bars.
1911 to now
The clock tower still stands beside the post office
The Cadeia da Vila de Sintra has carried the mail ever since Marques da Silva converted it in 1911. The old clock tower, once sealed off from the jail to stop prisoners escaping through it, still stands beside the post office today. The walls here held a king's would-be assassins, a novelist writing through his cell bars, and decades of ordinary prisoners.
1969 to 1984
Scouts inherited the old prison building
The Comarcã prison itself closed to regular use in 1969. For a few years the building served as a barracks for the Portuguese Legion, a state militia from the dictatorship years. In 1974, after the Carnation Revolution ended that regime, the Portuguese Communist Party occupied the building. A decree issued in 1972 had already ordered the prison's formal closure, effective that October 1.
The jail you're standing beside, meanwhile, had long since settled into its quieter life as a post office. A decade later, in 1984, the old prison building nearby was handed to Sintra's Scout troop, Grupo 93, for fifty years, to use as its headquarters and store its camping gear.
The building functions today as Sintra's post office, with the old clock tower standing beside it.
Read the ground you are standing on
Every person, building and event in this story opens into its own dig in the app — and Strata will dig the ground under your feet instead, wherever that is, in about a minute, with every source shown.
Sourced records, high and medium confidence. Era background is marked as such.
Prehistoric
2835 BC–2344 BC
Carbon dating from sites near Sintra has produced results as old as 2835 to 2344 BC and even further back, to around 9222 to 8629 BC, from material gathered a short distance from town.
Excavations around Sintra have turned up Roman and Iron Age habitation layers, including a necropolis and settlement remains within a few hundred meters, and a Roman villa at Abóbodas 3.5 kilometers away.
The hilltop Castle of the Moors, built around 1147 by Moorish rulers before falling to the Christian reconquest, stands half a kilometer south of this square.
King Afonso Henriques and Queen Mafalda donated land at the corner where you stand, now Rua da Pendôa, to Gualdim Pais, Grand Master of the Knights Templar.
The palace beside you, a National Monument of Portugal, has stood as a royal residence since at least 1400 and bears the scars of earthquake and centuries of rebuilding.
Afonso VI of Portugal, born and died in Sintra, lived his final years as a captive, and Pedro III, who became king a century later, also died here in 1786.
The great Lisbon earthquake of 1755 damaged the 12th-century Igreja de São Martinho on the Praça da República and collapsed the tower over the Sintra National Palace's Arab Room nearby.
South African poet Roy Campbell, cartographer John George Bartholomew, architect Raul Lino and socialite Mary Garman are all buried in São Pedro de Penaferrim Cemetery, a couple of kilometers away.
The building was the Cadeia da Vila de Sintra, the town jail, rebuilt and expanded in 1822 by builder Pedro d'Oliveira and used as a prison until 1911.
What happened at the Sintra town jail in 1908?
After a failed attempt to kill the king in January 1908, men suspected in the plot were held in the Cadeia da Vila, a few steps from the post office building.
Why was the passage between the jail and the clock tower sealed?
On 4 October 1852 the town chamber ordered the passage between the tower and the prison sealed shut because officials worried prisoners were using it to escape.
When did the jail become the Sintra post office?
In 1911 architect A. Marques da Silva converted the former prison into a station for mail, telegraph and telephone service.
Which writer was imprisoned in the old Sintra jail?
Novelist Camilo Castelo Branco was imprisoned in the Cadeia da Vila during the 1800s and wrote while locked inside its cells.
What replaced the old jail as Sintra's prison?
The Cadeia Comarcã, a hexagonal prison designed by architect Arnaldo Redondo Adães Bermudes, opened on 13 June 1909 on the grounds of the former São Sebastião Cemetery.
