The quick answer

Use at for an exact point, in for an enclosed space, and on for a surface. The right word depends on the shape of the place, not on how important it is.

The rule

At marks a precise point: a bus stop, a door, an address, a building you are visiting for a reason. In marks a space with something around it: a room, a box, a city, a country. On marks a flat surface that something rests on: a table, a wall, a page, a floor.

A few fixed uses do not follow the shape rule and must be learned as they are: at school, at work, at home, and public transport takes on (on the bus, on the train), while small private vehicles take in (in the car, in the taxi).

Form

Examples

• Meet me at the station.
• My parents live in Madrid.
• The keys are on the shelf.
• She is at work today.
• The children are playing in the garden.
• I saw your name on the list.

Common mistakes

• ❌ I am in the bus stop. → ✅ I am at the bus stop. A bus stop is a point, not a space.
• ❌ She lives at London. → ✅ She lives in London. Cities and countries take in.
• ❌ I go to school in the bus. → ✅ I go to school on the bus. Public transport takes on, not in.
• ❌ The picture is in the wall. → ✅ The picture is on the wall. A wall is a surface, so it takes on.