Kalutara sits next to the broad estuary of the Kalu Ganga, or “Black River”, from which it takes its name. Kalutara was formerly an important spice-trading centre, controlled at various times by the Portuguese, Dutch and British. Nowadays it’s more famous as the source of the island’s finest mangosteens (in season June to September). Kalutara announces its presence via the immense white dagoba of the Gangatilaka Vihara, immediately, south of the long bridge across the Kalu Ganga. The dagoba was built during the 1960s on the site of the Portuguese fort and has the unusual distinction of being the only one in the world which is entirely hollow – you can go inside the cavernously echoing interior, largely covered in a sequence of 74 murals depicting, various scenes from the Buddha’s life. Outside, a sequence of donation boxes line the roadside, popular with local motorists, who frequently stop here to say a prayer and offer a few coins in the hope of a safe journey – if your’s travelling south, you’ll soon understand why.