>Apartments here only refer to rented dwelling units in multi-unit buildings. Apartments are never purchased, and are never in single-unit buildings. A purchase of a unit in a multi-unit dwelling is a condo.

We call everything a flat, whether it is a conversion of a house or purpose built. The estate agents like to use other terms, apartment maybe (which sounds "posher") but never Condominium.

Edinburgh and Glasgow have tenement flats that were purpose built in the late nineteenth century and are now considered to be rather desirable. There are also houses divided into two - an upper and a lower.

Examples can be found at the Edinburgh Solicitors Property Centre - look at city centre properties:
http://www.espc.com/BuyingAndRenting/buymain.asp