This urban waterworld is a fast-growing city tucked into a bend of the Parana River about 186 miles northwest of Buenos Aires. Slip into a kayak or take a cruise for the best river views, or hit the city centre, bustling with discos, theatres, pedestrian malls, restaurants and parks popular with cyclists. A national monument on the riverbank honours the city's historic role as the site where the Argentine flag was first flown.