The postal History of Hong Kong dates back to 1841. From then till 1846 it was located in Garden road. Later it was relocated to Queen's road Central. I heard that it was one of the first buildings along the Queen's central. Then in the year 1911 it was moved to Des Voeux Road and Pedder Road, which is named after Mr. Pedder who was the first Harbor Master of the Port. It is fondly known as "The old lady of Pedder Street". The GPO building is considered an architectural masterpiece.
Hong Kong Post issued a stamp on 29th April 2014 depicting the Pedder Road GPO building, which was operational from 1911 to 1976. It is an odd shaped stamp issued under the title "A Journey Through Hong Kong's Postal History".
Below is the reverse side of the above miniature sheet, where you can see the shape of the stamp clearly.
The current GPO is in Conaught Place near Jordine House, Central Hong Kong.