Colonia del Sacramento, Uruguay , is a historic riverside town located 1 hour by ferry from Buenos Aires across the Río de la Plata . Founded by the Portuguese in 1680 , it is Uruguay’s oldest city and a UNESCO World Heritage Site , famous for its cobblestone streets, colonial architecture, and waterfront sunsets. Colonia del Sacramento is worth visiting as either a day trip from Buenos Aires or an overnight stay for a quieter and more romantic atmosphere. Why travelers vi