set foot on (something or some place)
To physically board something or travel to some place. As soon as I set foot on that train, I knew I'd never see my hometown again. It was her very first time setting foot on foreign shores.
set foot
1. set foot in. Enter, as in I'll never set foot in this house again.
2. set foot on. Step on, as in We were so happy to set foot on dry land. [c. 1600]
set foot somewhere
COMMON If you set foot somewhere, you physically go there. I never expected to set foot on British soil again. Poor kid, he thought, little did she know what lay ahead of her even before she set foot on foreign soil. I am not letting anyone else set foot outside this house.
set foot on
(or in) enter; go into The phrase is usually used in negatives or questions.