POLAND // Descend deep into a strange, dimly lit netherworld, full of artistic, architectural and spiritual treasures - all made of salt. Wieliczka operated as a salt mine from the 13th century all the way to 1996 and has been welcoming tourists for nearly 300 years. Reaching depths of 327m (1072ft), the mine has 287km (178 miles) of tunnels. Its labyrinthine reaches contain chapels, a saltworks museum, hundreds of salt sculptures and much more. The highlight is the gargantuan Chapel of St Kinga, with its ornate salt chandeliers and altarpiece. There's also an underground lake and a 'subterraneotherapy' spa, which takes advantage of the purported health benefits of the mine's unique microclimate. All we can say is, it's surreally salty down there.