Kalutara presides over the mouth of the Kalu Ganga River, less than an hour’s drive from the capital, Colombo. It was once a thriving spice port, ruled by the Portuguese, Dutch and British, but is now better known as the source of Sri Lanka’s most flavoursome mangosteens, which you’ll see piled in purple heaps in the local market from May until late-August. Anyone keen to explore should start at huge white dagoba beside the river bridge. Built on the site of an old colonial fort, the Gangatilaka Vihara is one of the few in Sri Lanka that you can actually go inside as the massive structure is entirely hollow!