Looking up...
She rented a cozy apartment in the city center.
She found and rented a small, comfortable living space in a multi-unit building.
a single unit of housing in a larger building, typically on one floor
The apartment had two bedrooms and a spacious living room.
The housing unit contained two sleeping areas and a large common area.
In British English, 'flat' is often used instead of 'apartment'.
Remember that 'apartment' is more common in American English, while 'flat' is preferred in British English.
The plural of 'apartment' is 'apartments'.
From Old French 'apartement', meaning 'division', from 'apartir' (to divide)
In American English, 'apartment' is more common than 'flat'. In British English, 'flat' is preferred.