2) 15 of the world’s largest 25 hotels are in Vegas. By number of rooms, the MGM Grand Hotel & Casino is the largest hotel in the country with 5,043, and depending on your source, it is the second largest in the world. With 3,933 rooms, Bellagio hotel has more rooms than the population of Bellagio, Italy (2,945). Currently there are 150,544 hotel rooms in total in Las Vegas.