A. In: in a room; in a garden; in a line; in bed; in the sky; in an office; in a photograph; in a book; in a letter; in the front; in the back of the car; in hospital; in prison; in jail.
A1. use in when we are thinking about the building itself. (not at the hotel)
A2. normally use in with cities, towns and villages. But we can use at or in when we think of the place as a point or station on a journey.
B. At: at the bus stop; at the door; at the window; at the top (of); at the end (of); at the front; at the back of a building; at theatre; at sea (= on a voyage); at home; at work; at university; at a party or at a concert (at an event); at (an event takes) places; at the station; at airport; at somebody’s house; at the doctor’s; at the hairdresser’s etc.
B1. at the corner or on the corner of a street.
C. On: on the wall; on the nose; on a page; on the island; on the right-hand side; on the ground floor; on a map; on a Manu; on a farm; a place in on a river/ on a road/ on the coast; on the way; on the front; on the back of a letter/ piece of paper etc.
C1. We usually say on a bus; on a train; on a plane; on a ship but in a car/ in a taxi. We say on a bike (= bicycle)/ on a motorbike/ on a house.