Inscriptional evidence suggests that the Phnom Kulen plateau to the north-east of Angkor in Cambodia was the location of Mahendraparvata—an early Angkorian capital city and one of the first capitals of the Khmer Empire (ninth to fifteenth centuries AD). To date, however, archaeological evidence has been limited to a scatter of small and apparently isolated shrines. Here, the authors combine airborne laser scanning with ground-based survey to define an extended urban network dating from the ninth century AD, which they identify as Mahendraparvata. This research yields new and important insights into the emergence of Angkorian urban areas.