According to Vegas.com, a person has to be 21 years of age to legally gamble in a Las Vegas casino. People under 21 can usually walk through casinos, but not stop inside the casino, on their way to a restaurant or show.
Vegas.com states that the Bellagio is exceptionally restrictive, excluding anyone under 18 from entry to the hotel unless that person is a registered guest in one of the hotel's rooms. The drinking age in Las Vegas is also 21. Establishments that sell alcohol or provide gambling activities generally require proof of age in the form of government-issued photo identification before a patron can enter.