As of now, only Lodhi Garden is open which consists Lodhi monuments, but you can visit the following after the lockdown-
1.Red Fort
2.Humayun's Tomb
3. Mehrauli archaeological park
4. Qutub Minar Complex
5. Mehrauli Village
6. Tughlaqabad fort
7. Jantar mantar
8.Old Fort
9. Hauz Khas Village
10. Gates of Delhi (all of them)
11. Jama Masjid
12. Safdurjung tomb
13. Sunder Nursery
14. Kotla Mubarakpur
15. Ridges of Delhi (Northern, Central, South-central, Southern)
16. Qila Rai Pithora