A public space, either existing or located in an existing built environment, is a place that is accessible to the general public, i.e. accessible to anyone.
It may be located in a building dedicated exclusively to accommodating people (e.g. a hotel), or in a multi-unit residential building (i.e. with at least 5 separate apartments), which may have a place open to the public on the ground floor (e.g. a butcher's or doctor's surgery).