evidence: Khao Phra Wihan ('Preah Vihear' in Khmer) is a large Khmer temple ruin perched dramatically on a cliff 500m above the plains below. It's just over the border in Cambodian territory and currently not accessible from the Thai side due to a border dispute. All that is open to visitors now are scenic overlooks and some minor Khmer ruins, all of which are interesting, but not really worth the 400B admission fee. Khao Phra Wihan National Park