Erected on the rim of an extinct volcano, with sweeping views south to the Dangrek Mountains on the Cambodian border, Phanom Rung is the most spectacularly sited of Thailand’s Khmer temples. The shrine, originally dedicated to Shiva, is surmounted by a magnificent tower, which during the full moon phase of April each year becomes the focus of an exuberant festival, when the stonework is adorned with vibrant silk streamers and banners. A 139-mile (225km) ancient highway, paved in laterite, once ran all to way from Angkor to Phanom Rung, and then north to Isaan’s other great Hindu shrine, Prasat Hin Phimai, which can be visited on the same day.