The largest of Penghu's five fortress sites, this was one of a pair rebuilt in 1887 following the end of the Sino-French War. Four heavy Armstrong guns (up to 12-inch bore) still sit on the far bastion and it's fun to spend five minutes burrowing through the tunnels which are plastered but totally bare.
The location is lonely and windswept apart from the large visitor centre (free) which gives historical context and introduces Penghu's other forts.