Vatican Museums are a series of Christian and art museums within the Vatican City. Over the centuries, the Popes gathered an immense collection of 70,000 works of art, and 20,000 of them are available for public observation. It's a place to discover some of the world's most prominent masterpieces of Renaissance art along with classical sculptures.
The museums were founded back in the early 16th century. The founder was Pope Julius II who brought the first marble statue to the public display. It was the statue of Laocoön and His Sons, depicting a Trojan priest with two sons being attacked by giant serpents. The Pope spotted the statue on January 14th in 1506 in one of the Roman vineyards—near the Basilica of Santa Maria Maggiore and immediately decided to buy it from the vineyard's owner. A month later it was exposed for the public in the Vatican. That's how it started.
Today, Vatican Museums consist of 54 galleries making it one of the world's largest museums. Some of the most brilliant ones are the Sistine Chapel, ornated by Michelangelo, and Stanze di Raffaello, featuring the art of Raphael.
Vatican Museums are one of the unmissable attractions on a trip to Rome. In 2017 for instance, they were visited by 6 million people and became the renowned as the world's 4th most visited art museum. Needless to say, it's always crowded, but particularly between March and mid-November. If you come during the peak season, make sure to buy your tickets online not to wait in the queues, or book a tour. The low season, late November through February, is much better (excluding Christmas and New Year's).
The attraction is open daily Monday to Saturday, 9 am to 6 pm with the last entry at 4 pm. Note that visitors are asked to leave 30 minutes before the closing time. Museums don't operate on Sundays, apart from the last Sunday of each month when they offer free entrance. Free Sundays are the most crowded. Moreover, the hours are limited to 9 am and 2 pm with the last admission at 12:30 pm. Saturdays are also crowded, as all the weekenders head to the Vatican. Therefore, it's better to choose a weekday. The best time to visit Vatican Museums is in afternoon, around 3 pm, when the crowds thin out. Also, note that on Wednesday, Vatican Museums may be closed till noon due to Papal Audience.