usage of the gpo building today

Sydney GPO Heritage Building Current Usage

Currently, Australia Post maintains a presence in the form of a "Post Shop" at the corner of Martin Place and George Street but the rest of the building is devoted to shops, cafes, restaurants and bars as well as a hotel and function rooms.

The Westin hotel and Macquarie Bank office towers stand at the rear of the courtyard, which was converted into an atrium. The ground and lower ground floors house retail premises with the anchor tenant operating all the food and beverage operations known collectively as the "GPO Grand" (GPO Restaurants and Bars).

Source: Wikipedia