Being India's capital and having immense historical significance, Delhi can surely delight travelers with its interesting tourist options. I can try to list some of them :
1) Rashtrapathi Bhavan - official residence of Indian president.
2) Rajpath - formerly known as 'King's Road' during British era, Rajpath is a ceremonial road running from Rashtrapathi Bhavan to Raisina Hill, where majority of the significant administrative buildings of Govt. of India resides.
3) Indian Parliament - Supreme legislative body of the country of India.
4) Jantar Mantar - An ancient Indian astronomical observatory built by Raja Jai Singh.
5) Red Fort (or 'Lal Kila') - Built by red sand stones, it was the main residence of Mughal emperors. But now, it is significant as the venue for major events like India's independence day flag hosting, etc.
6) Humayun Tomb - Listed as a world heritage center by UNESCO, it was built by Humayun's wife Haji Begum and is considered to be a wonder in Mughal Architecture constructed with white marbles and red stand-stone. Even Taj Mahal owes its design to Humayun Tomb.
7) Qutub Minar - Another UNESCO listed world heritage center, this ancient structure built by Mughal king Qutub-ud-din-Aibak will surely amaze the visitors with its height.
8) Lotus Temple - A temple in the shape of Lotus by the Bahai religion.
9) Akshardham Temple - World's largest Hindu temple built by BAPS spiritual organisation.
10) Delhi's Jama Masjid - India's largest mosque, built by Mughal king Shajahan.
11) Raj Ghat - This memorial of India's father of nation, Mahathma Gandhi includes the exact spot where he got assassinated.
12) Agrasen Ki Baoli - It is a fort in Delhi which is very much famous as a haunted place.
13) Chandni Chok - Delhi's traditional, bustling market place.
14) Shankar's International Doll Museum - Established by the famous cartoonist K.Shankar Pillai, this museum houses 6500+ dolls from different parts of the world.
15) Select Citywalk - A premier shopping mall in Delhi spread over 13lakh square feet.
16) National Museum of India - One of the largest museums in Delhi housing several manuscripts, paintings, and many more.
To conclude, I would also like to add that majority of the travelers will include Agra in their Delhi-visit, to see Taj Mahal. So, are you planning a Delhi visit ?!