“Nobody should be allowed to walk on 1,000-year-old stones,” says Jeff Morgan, executive director of the U.S.-based Global Heritage Fund. He says limits on tourists at the temples are decades overdue. The influx hastens the deterioration of edifices already buffeted by invasive tropical vegetation and monsoon rains. The relentless tread of feet and the fumes from heavy traffic wear away the soft sandstone. Oily fingers harm the magnificent bas reliefs. Noisy crowds rob visitors of near-mystical moments of quiet contemplation or the chance to imagine they are jungle explorers discovering a lost city. Too many tourists are not Angkor’s only woe. The UNESCO World Heritage Site and its gateway town of Siem Reap are also beset by crass development, alleged corruption and endlessly delayed plans on how best to preserve the temples.