Mirage City
Seeing the merchant's back disappear up the incline that led outside their little 'underground base', anitra turned her attention back to the slavegirl, licking her lips.
27 Ounces: A Story of Eight And One Half Ponies
Some said the caravans provided resources to secret groups building underground bases. some said the human liberation front imagined they might survive the expansion of equestria in such places.