There are many special hotels around the world. In Greenland, there is a hotel made out of ice. In Turkey, there is a cave hotel. And in Bolivia, there is the Salt Palace Hotel. Thousands of years ago, the area around the Salt Palace Hotel was a large lake. But over time, all the water disappeared. Today, the area has only two small lakes and two salt deserts. In the early 1990s, a man named Juan Quesada built the hotel. He cut big blocks of salt from the desert and used the blocks to build it. Everything in the hotel is made out of salt: the walls, the roof, the tables, the chairs and the beds. The sun heats the walls and roof during the day. So the rooms stay warm at night, though it's cold outside in the desert. The hotel has twelve rooms. A single room costs $40 a night, and a double room $60. A sign on the hotel's wall tells guests, "Please don't lick   the walls." What is the passage mainly about?
A large lake. A special hotel. A beautiful wall. A famous desert.