Jantar mantar is central place for any kind of demonstration. I saw this place when Anna hazare was on strike for Lokpal. This is one of astronomical observatory made by Raja jaya singh. Other observatories are in Jaipur, mathura, Varanasi. It shows how India is researching in its own way. Most fabulous, lushgreen, very close to CP. You have some type of scientific understanding to understand the various instruments.