What is the material used to construct the walls of this building?

Palacio de Sal, Spanish for "Palace of Salt", is a hotel built of salt blocks.

The original, pictured, was located in southwest Bolivia, near the crest of the Andes at an altitude of 3,656 metres. Salar de Uyuni, the world's largest salt flats, has long attracted tourists. Building a hotel required construction materials, which are scarce in the area. Therefore, it was logical to erect a hotel made of salt, which is in ready supply at Salar de Uyuni.

The original was built in 1993-1995 out of salt blocks in the middle of the Salar de Uyuni, and soon became a popular tourist destination. It had 12 double rooms, a common bathroom, and no shower. With no sewage system, waste was collected manually. Sanitary problems caused serous environmental pollution resulting in the dismantling of the hotel in 2002.

Around 2007, a new hotel was built in a new location at the eastern edge of Salar de Uyuni, 25 km away from the town of Uyuni, 350 km south of Bolivia's capital La Paz. The building was constructed of about 1 million 35 cm salt blocks, which are used for the floor, walls, ceiling and furniture, including beds, tables, chairs and sculptures. The sanitary system has been structured to comply with government regulations.

There is a rule against licking the walls to prevent degradation.