Relax and take a deep breath!
Humayun's Tomb is a wonderful park with astonishing monuments. Even though, as with most places in India, foreigners have to pay a lot (250 rupees) to enter, it is worth it if you bring some time and just stroll around and relax for a while. In the middle of Delhi, you can hardly hear any noise from the mad traffic, and really find peace here. It is lovely! For history buffs a must. Enjoy!