Tainan's Chihkan Towers/Fort Provintia/Sakam Tower, Taiwan
Chihkan Towers (the current name, by the way) is the most popular historical site in Tainan (according to the ticket). Apparently it looks beautiful at night as well. It's accessible along the tourist bus route (ask for details at the TIC) or take a taxi. It's open 8:30 AM to 9 PM; admission is only NT$50. If the crowds are lighter, you can really enjoy it, but as part of a long, hot, rushed, crowded day, I couldn't appreciate this as much as I would have liked. Still, a must-see if you go to Tainan.