Colonia del Sacramento is a city in southwestern Uruguay, by the Río de la Plata, facing Buenos Aires, Argentina. It is the oldest town in the country and capital of the departamento of Colonia.

History

Founded in 1680 by the Portuguese, Colonia was later disputed by the Spanish settled on the opposite bank of the river at Buenos Aires. The colony kept changing hands from crown to crown due to treaties like the Treaty of Madrid in 1750 and the Treaty of Santo 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 eastern bank (Banda Oriental) of Uruguay was seized by the Rio de Janeiro government.

Today, the city has expanded to the east, but its original part still keeps the "disarranged", terrain-fitting street plan in the oldest part, built by the Portuguese, contrasting nicely with the wider orthogonal calles in the Spanish area.

The historical parts of Colonia are named by UNESCO as a World Heritage Site.