Riyadh: At least 542 caves and sinkholes discovered in Saudi Arabia’s Northern Borders region offer more destinations for the increasing number of tourists, adventurers and researchers interested in these structures, the Saudi Press Agency reported on Sunday. Of varying shapes, these structures offer a glimpse into the past with their unique geological formations, said the report, quoting Burjas Al-Falih, a speleologist and a member of the Afaq Society for Astronomy.