Udon Thani is a big, brash city with one of the largest expat populations in Thailand. The city boomed on the back of the Vietnam War as the site of one of the largest US air bases, and it subsequently became the region's primary transport hub and commercial centre. The town itself doesn't have many must-see attractions, but there are some interesting spots in the surrounding region.
Read more: http://www.lonelyplanet.com/thailand/udon-thani-province/udon-thani#ixzz3tBN3csjh