This gigantic network of quarry-tunnels date back centuries but are most intriguing for their occasional charcoal murals and the stories linked to their use in WWII as a virtual city for hiding the population during times of bombardment.
Check the website for tour times and meet the guide behind the Buitengoed Slavante cafe, arriving a little before the appointed time. Booking ahead online incurs a €1 extra fee but ensures your place should the visit be oversubscribed.
Tours are less frequent than to the North Caves but in reality both systems are part of the same extraordinary underground maze that once added up to 230km of tunnels (some 80km remain).