Built in 1907, this is Taiwan's oldest, operating, paid hot spring. The small pools are segregated by sex. Bathing is nude, women must tie long hair back. The stone is original and contains hokutolite, a weakly radioactive crystalline substance found only in Beitou and Japan.
The water is a scorching 44°C degrees. Don't forget to shower and wash your feet with the buckets provided on the edge of the pool before getting in. There are also several private pools (NT$400-750, depending on size of room).
This is a simple and inexpensive option without the crowds of Millennium. Numbers of men are capped at 35, and women at 25.