On a magnificent rock you can find a palace from the 5th century AD. The foundations are still there, some pretty rock drawings, the old swimming pool... It's a quite impressive place. Just don't go on a full moon, unless you like huge lines of local tourists.

Colombo
Dambulla
Galle
Kandy
Kurunegala
Negombo
Nugegoda
Sigiriya
Trincomalee
Unawatuna
Unawatune
Wattla