The CBD, or Central Business District, is a concept similar to the downtown of US cities. It is, by definition, the area in which most real “business” takes places (think Wall Street). It might also be referred to as the City Centre.
The CBD is the place to find high-end retail, overpriced coffee chains, 9-5 desk jockeys, and kitschy tourist junk. Unlike the States, real estate is relatively cheap in the CBD, probably because people here like the idea of “home” to mean something more than the floor where you crash after a 16-hour, caffeine-fueled day of being an office slave.