
Time for some history!
The ancient Hindu kingdom of Champa established the first buildings at the sacred/ritual site of My Son in the 4th century, and continued to expand through the 13th century. Although the Champa and Angkor kingdoms were separate (and known to war with one another), the buildings bear some resemblance (I'm told) to Cambodia's Angkor Wat. At any rate, the Champa kingdom fell apart around the 1300s, and the site was presumably abandoned and/or forgotten, and was only rediscovered at the end of the 19th century. What remained of the site was all but flattened during the American war, but parts of it are now being excavated and restored, in what I am sure is a painfully slow process. Some of the remaining walls bear bullet holes, and there's a large bomb crater (now overgrown with weeds, but the depression remains) in front of one of the sanctuaries. (To be fair, the Americans probably weren't attacking indiscriminately or to purposely destroy the cultural history; the site's location and geography had made it a good headquarters for the Vietnamese leaders.)
A little bit of trivia for you: the method that the Cham originally used to lay the bricks (or rather, to make them stick together) remains unknown; you can tell which portions of wall are original and which are the product of recent reconstruction by looking at the bricklaying. The Cham bricks lie packed flat on top of each other, with virtually no separation, while the 20th-century work looks more like the regular brick-and-mortar pattern with which we're all familiar.