Crystal Mines

The Crystal Mines is a place where people are put to prison.
The Mines supply the crystal used in building the skyscrapers and other buildings of Wondertropolis, as well as possibly supply crystals for other uses (entertainment, fire crystals, ammunition). 
Early in Alyss Heart's reign, many prisoners were wrongly incarcerated here, and Alyss signed many official pardons in order to free them. Jack of Diamonds was imprisoned here until his liberation by King Arch.