Mina El Edén is a former silver mine converted into one of Zacatecas' most popular sights. A small train and guided route take visitors into the tunnels, past mineral displays and old workings that hint at the scale of the mining economy.
It is touristy, but worthwhile. Pair it with the Teleférico station nearby so you move from underground Zacatecas to the aerial view in one neat loop.