The Umaid Bhawan Palace in India is part hotel, part royal residence. When it was completed in 1943, it was the world's largest home, and required the work of more than 3,500 builders. Construction of the palace cost more than $225,000 USD (11 million Indian rupees) and took 15 years to complete [source: Harbord]. One of the palace's most spectacular features is its indoor pool, which is located deep underground in the heart of the building. Known as the "Zodiac," the pool is circular and themed in a classic Art Deco style. The bottom of the pool is covered with tile mosaics depicting the signs of the Zodiac, while the walls and ceilings in the room are covered with thousands of one-inch (25.4-millimeter) tiles covered in gold. Today, hotel guests can swim in the pool along with members of India's royal family, who still live in their own private wing of the palace.