Answer : 4. "Chandigarh"
Explanation :

1. The famous Rock Garden is located in Chandigarh.

2. The first rock garden in India has been established in Chandigarh.

3. It was constructed in the year 1957 by Officer Nek Chand.

4. The first rock garden of Chandigarh is also known as Nek Chand Rock Garden.

5. It is situated near Sukhna Lake.