Wat Phumin is Nan's signature sight. The chapel is built in a cross shape, with four entrances guarded by long naga forms, and the interior is filled with late-19th-century murals by Tai Lue artists. The famous "whispering" couple gets the postcards, but the everyday details around them are just as good: clothes, courtship, foreign visitors, and village life painted with unusual humour.
Come early or late if you can. The building is small, and the murals reward time more than a quick photograph.