Colonia del Sacramento is in Uruguay. It is filled with old colonial buildings and cobbled streets, and is inscribed on the UNESCO World Heritage List.
Colonia del Sacramento (Nova Colonia do Santissimo Sacramento) was founded in 1680 by the Portuguese (Manuel Lobo), sandwiched in between the Portuguese colony of Brazil and the Spanish Vice Royalty of the River Plate (later Argentina, Uruguay and Southern Brazil). Its strategic position and use as a smuggling port meant that its sovereignty was hotly contested and the city changed hands several times between Spain and Portugal.
Founded in 1680 by Portugal as Colônia do Sacramento, the colony was later disputed by the Spanish who settled on the opposite bank of the river at Buenos Aires. The colony was conquered by José de Garro in 1680, but returned to Portugal the next year. It was conquered again by the Spanish in March 1705 after a siege of five months, but given back in the Treaty of Utrecht. Another attack during the Spanish-Portuguese War, 1735-1737, failed.
It kept changing hands from crown to crown due to treaties such as the Treaty of Madrid in 1750 and the Treaty of San Ildefonso in 1777, until it remained with the Spanish. It then transferred to Portuguese control again, and later to the Brazilians after 1816, when the entire Banda Oriental (Uruguay) was seized by the Rio de Janeiro government and renamed the Cisplatina province.
Now part of the independent country of Uruguay, Colonia del Sacramento has expanded to the north and east, but the original Barrio Histórico (historic quarter) retains its irregular, terrain-fitting street plan built by the Portuguese, contrasting with the wider, orthogonal calles in the newer Spanish area.
PLACE TO VISIT
The Barrio Histórico (historic quarter) section of Colonia del Sacramento is designated a World Heritage Site by UNESCO. It is a popular tourist attraction for visitors from Buenos Aires, and there is frequent ferry service across the Río de la Plata between the two cities, with hydrofoils completing the journey in just 50 minutes. The historical section of Colonia, which has some cobblestone streets built by the Portuguese in the 17th century, is within walking distance of the ferry terminal. Among the notable visitor attractions around the tree-lined Plaza Mayor (main square) are:
Portón de Campo – the City Gate and wooden drawbridge
Lighthouse and convent ruins of the 17th century Convent of San Francisco
Basilica del Sanctísimo Sacramento – the Basilica of the Holy Sacrament, built of stone by the Portuguese in 1808
Portuguese Museum – constructed in the 18th century, it exhibits Portuguese furnishings, jewellry, uniforms and old maps of Portuguese naval expeditions
Casa de Nacarello – an 18th century Portuguese house
Municipal Museum – rebuilt by the Spanish in 1835 as the Casa del Almirante Brown, it exhibits artifacts and documents of the city's different periods and cultures
Viceroy's House – the Casa del Virrey, reconstructed from the original ruins
Iglesia Matriz – the oldest church in Uruguay, dating from 1695-99
Plaza de toros Real de San Carlos, a Bullring included in an old tourist complex now abandoned.
HOW TO REACH
Two daily boat connections arrive and depart from Buenos Aires and are the main connection to Argentina. A fast expensive one and a cheap slow one. The fast Buquebus catamaran ferry (one hour) costs ca. 60 USD return and is usually quite crowded with day tourists and travel groups. Make sure you book in advance for weekends and the peak season (Christmas until the end of February). The slower boat costs 102 Pesos (from Buenos Aires) round trip, and takes about 3 hours.
An cheaper possibility is to take a boat from Tigre to Carmelo in Uruguay. From Carmelo, take a bus, which run every two to three hours from the center of the city to Colonia. Great landscape and also drops off kids from school along the way.
There are several connections by bus from Montevideo to Colonia. Be careful with people telling you that all buses are booked out. This is in general not true and a taxi is much more expensive. For the peace of your mind buy a bus ticket upfront to avoid rare disappointment.
If you want to extend your stay in Uruguay or Argentina then Colonia is a good place because upon arrival you are granted a new 90 day tourist visa for either country.

