The Río de la Plata is the broad estuary dividing Argentina and Uruguay. On its southern shore sits Buenos Aires, while Uruguay's buzzing capital Montevideo marks the point on the northern shore where estuary turns to Atlantic.
The main draw on the Uruguayan side is Colonia del Sacramento, the oldest city in the country, whose Portuguese and Spanish Barrio Histórico (old town) is a UNESCO World Heritage site. Pastel-coloured colonial houses, cobbled lanes, vintage cars and obsolete cannons hark back to the grand old days, while contemporary restaurants and boutiques draw thousands of visitors from Buenos Aires (connected by ferry in under an hour). Despite the summer influx, it's a sleepy place with lots of charm and little of the hassle of some Latin American countries. Stay the night and you'll feel as if you have the place almost to yourself.