Discovered by chance in 2001 by Vietnamese miners, the Phú Diên tower had been buried under sand dunes for nearly 1,000 years. It was likely built in the 8th century by the Cham civilization using fired clay bricks, interlocked without mortar. It's located on a beach just 50 meters from the Pacific Ocean and is now in a glass enclosure to protect against coastal erosion. Its purpose remains unclear, as it lacks carvings of deities that would indicate it was a religious site.