The ancient Khemer temple complex of Preah Vihear is in Cambodia near the Thai-Cambodian border. Some of the land around the temple is claimed by both countries. The border dispute has heated up recently, as Cambodia has attempted to get Preah Vihear declared a World Heritage site.
Cambodia submitted a plan on its own to get the temple recognized by Unesco as a World Heritage site. Thailand has opposed the plan, claiming that the submission did not recognize its rights, and strongly protested recognition. After negotiations failed, Unesco ended up delaying its decision, citing technical deficiencies in Cambodia's application.
Unesco's decision has not resolved the issue, as Cambodia can undoubtedly refile and correct the identified issues. It is unclear whether Thailand and Cambodia can resolve their issues. Some here have made it an issue of national pride; claiming that Thailand is losing sovereign territory, so the issue definitely won't go away quietly.