Dehradun is the capital of a newly formed state- Uttarakhand. It lies in the foothills of Himalayas.
There are loads of places to explore in and around Dehradun. You can plan short treks, go for
river rafting, visit historical places and explore National parks.

It is quite close to Rishikesh, Haridawar and Mussourie. These are also must see.