Red Fort:
The Red Fort (Lal Qila) is one of Delhi's top tourist sights. A brilliant red sandstone fort built by the Mughal Emperor Shah Jahan (who also built Agra's Taj Mahal) as his ruling palace. Completed in 1648, the years since have not treated the buildings kindly: the rooms have long since been stripped of all objects, the marble inlays are long gone and quite a few buildings are off limits. Still, the scale remains imposing and the gardens are kept lush and green even in midwinter.

Humayun's Tomb:
Humayun's Tomb in south Delhi, near Hazrat Nizamuddin station, is one of Delhi's three UNESCO World Heritage Sites. Open daily from sunrise to sunset, entry is 10/250 rupees Indians/foreigners.
The tomb is in large, immaculately maintained gardens in the Persian Char Bagh (four corners) style that were thoroughly renovated in 2003 with the Aga Khan's help and are consequently probably the best in Delhi. As you enter the complex, the first major structure on your right is the bulbous, octagonal tomb of Iza Khan, a court noble who built it in his own lifetime, some 20 years before Humayun's tomb. As you pass through the first gate, you will glimpse the dome of the tomb and enter a floral path leading to the second (West) gate, which now acts as the entrance to the giant central garden.

Qutub Complex:
This complex in Mehrauli, houses structures dating from the Slave Dynasty (1206-1290) and is designated as a UNESCO World Heritage Site. The gardens are kept in excellent shape, making this a popular relaxation and picnic spot. Open daily from sunrise to sunset, entry is 20/250 rupees Indians/foreigners. Light-and-sound show held most nights after sunset. Now easily accessible via Qutub Minar station on the Metro Yellow Line.

Museums:
Gandhi Smriti: 10AM-5PM (Closed Monday). This estate is the site of Mahatma Gandhi's martyrdom. Includes a museum celebrating his life and the room he lived in during his final days.

International Doll's Museum: Nehru House, 4 Bahadur Shah Zafar Marg. T-S 10AM-6PM. A museum of dolls from all over the country. You get to see the costumes and art from all over India, as well as some nice crafts. 10 rupees.

Parks and Gardens:
Lodhi Garden: is a peaceful park in the heart of New Delhi. Lodhi garden is ideal for morning walks in the hot season and for afternoon strolls and picnics during the cooler months
Nehru Park: is a large park in the new Delhi neighborhood of Chankayapuri, lying in the southwest.