launch pad 
(also launching pad)
noun
The area on which a rocket stands for launching, typically consisting of a platform with a supporting structure: figurative the small gallery has been a launch pad for many artists...
- The camera will be turned on fifteen minutes prior to launch and will show the orbiter and solid rocket boosters on the launch pad.
- What is an astronaut feeling as he's sitting on the rocket launch pad strapped into his pod at the brink of takeoff?
- These use a 1: 20 scale model of Vega and its launch pad to simulate conditions at liftoff.