If you have 2-3 hours to spend in Doncaster, there are a few things you can do:
Visit the Doncaster Museum and Art Gallery - This free attraction features exhibits on local history and art, and should take around an hour to explore.
Take a walk in Sandall Park - This large park features a lake, playground, and plenty of green space to wander around. Depending on how much time you want to spend, you can take a casual stroll or a longer walk around the park's perimeter.
Shop at the Frenchgate Shopping Centre - If you're looking to do some shopping, head to this indoor mall where you'll find a variety of stores. The amount of time you'll spend here will depend on how much shopping you want to do.
Explore Conisbrough Castle - This castle is a bit outside of Doncaster, but it's a great spot to visit if you have a car or are willing to take public transportation. You can tour the inside of the castle and take in the views of the surrounding countryside. Plan to spend around an hour here.
Overall, how you spend your time in Doncaster will depend on your interests, but these options should give you a few ideas of what to do with your 2-3 hours in town.