https://www.youtube.com/watch?v=m-uqwCTvGgA
On 6 August 2021, SpaceX briefly stacked Starship prototype SN20 on Super Heavy Booster 4 at Starbase, Texas — the first time the full ~120 m stack stood on the orbital launch mount.
The fit check confirmed interfaces between ship, booster, and pad before the vehicles were separated again for further work.