Courtesy of the Mercat Tours

Also called South Bridge Vaults, they are a series of chambers formed in the 19 arches of the iconic South Bridge in Edinburgh. It was built to link the Old Town’s High Street with the University buildings on the south side of the city, according to Historic UK. The city spans seven big hills. Only two of these high points are visible in the city center today – Castle Hill, atop which sits Edinburgh Castle, and Calton Hill.