Agra is famous for the Taji Mahal. It would take more than 3 hours to reach there and the road system from Delhi to the Agra is not really good.
1. How to go there?
In order to reach there, you may rent a car with a driver. You may also take a train but the trains in India is not so clean and efficient.
2. What to do?
Most of the Indian visit Taji Mahal,
(1) Taji Mahal
The entrance fees would be around 25 USD for foreigner and around 5 dollars to the local people. You may also meet some of the guides at the entrance. But tourist guides are not much required.