When prisoners finish their sentences, they move on. The prisons that keep them locked up do, too. Newer, larger facilities replace outdated ones. But, the high walls, locked gates, and watch towers of previously used jails and penitentiaries remain. The creepy compounds may give you chills as you imagine them housing dangerous criminals, but they’re even more eerie when you learn about the grisly events that happened within their walls and the spirits of prisoners past who may have stuck around. If you’re interested in visiting, plan ahead. Some facilities organize guided tours regularly, while others offer limited-time seasonal events. Still others are off-limits and can only be seen from afar.