Luang Namtha is a little town in northern Laos between Huay Xai and Oudam Xai, located in an area famous for the various minority villages.
In my opinion Luang Namtha itself has not a lot to offer. Most most guesthouses and tour agencies as well as the very interesting night market are located on the main street that leads through the town.
Maybe the only other site worth mentioning is the local market, located on a parallel street running south of the main road. It is interesting to walk around the rather large area with stalls selling fresh fruits, freshly prepared meat (and blood in bags) and other items the locals need. Do not expect to find lots of tourists souvenirs.
While the town itself is not that interesting, it cannot be said about the surrounding area, with is the reason people visit Luang Namtha – it is just beautiful. You can easily explore the area by renting a scooter or a bicycle, stopping at waterfalls or temples. Or you join one of the many treks to the national park – many offer real homestays in minority villages (where you sleep in a local house and get home made food – a great experience).