Rosemont is a city in Cook County in the state of Illinois, just outside of Chicago. It does enormous business as the primary hotel supplier for O'Hare International Airport, but has a couple of the region's best-known concert venues as well.
The CTA Blue Line has a stop in Rosemont.
PACE buses serve the area, and hotels can be expected to run shuttles to the airport. For anything else, though, you'll likely want to have a car.
There are quite a lot of hotels in Rosemont — see O'Hare International Airport for listings.