roof garden
US /ˈruːf ˌɡɑːr.dən/
UK /ˈruːf ˌɡɑːr.dən/

1.
a garden on the roof of a building
:
•
The hotel has a beautiful roof garden with panoramic city views.
•
They decided to install a roof garden to make use of the unused space.
a garden on the roof of a building