Prepositions of place
At and on
We use at to show a specific place or position.
Someone is at the door.
They are waiting at the bus stop.
I used to live at 51 Portland Street.
We use on to show position on a horizontal or vertical surface.
The cat sat on the mat.
The satellite dish is on the roof.
We also use on to show position on streets, roads, etc.
I used to live on Portland Street.