The Wesak festival is the most sacred Buddhist ceremony held every year in a hidden valley in Tibet. It celebrates the story of how the Buddha gained enlightenment and allows those seeking enlightenment today to think about the meaning of that path. Buddhists celebrate it in different ways in different counties. In Thailand, for example, the BBC says that people make special lanterns and in some ceremonies even release caged birds. In China, one might see dancing dragons during Wesak and in other other countries one might find ceremonies in which participants bathe Buddha statutes. Here's the program for a Wesak festival in California. And here is a nice introductory prezi on Buddhism. My thanks to Gary Abrahamian who tweeted the link to the video above and the prezi.