The finest day trip from Montevideo — an hour by ferry to Colonia del Sacramento, the UNESCO World Heritage colonial city on the Río de la Plata established by the Portuguese in 1680. The Barrio Histórico (Historic Quarter) is one of the best-preserved colonial streetscapes in South America: cobblestone streets, crumbling city walls, a lighthouse, 17th-century churches, and antique cars left where they stopped decades ago. The tour includes the ferry crossing both ways, a guided walk of the Historic Quarter, free time for lunch and exploring, and return to Montevideo by evening.