Former capital it may be, but the fire of 1827 destroyed more or less everything and Finns don't call it "the arse of Finland" for nothing. :) But do check out the cathedral and Aboa Vetus, which is mostly remarkable for how they managed to turn a couple of banged-up rocks and pottery shards into a passable museum, and Ars Nova if they've got something interesting going on. If the weather is nice, take the cruise through the islands to Naantali, where you can watch Japanese tourists taking pictures of people cavorting around in fat hippo suits.