Definitely some historical place.
Umm you can take him to some cafe and then go for some drive to a calm place( like cp or hauz khas) and propose him
You can book some personal area in a beautiful cafe with eye catching decor and surprise him . Or you can go for a long drive and propose him .
You can take him to a long drive and there in some dhaba suddenly suprise hime with ring. He will be amazed to see that because he will be thinking only of long drive and not this super suprise.
Historical Places. Amazing 🤩 Place.
Hauz khas, Lodhi Garden (fountain side), Safdurjung tomb, Humayun's tomb, Sanjay Van (very quiet, go for a walk and suddenly surprise him), at a restaurant on a romantic lunch/dinner date.
Historical Places. Very few people go there. Must try.