Admiralty House was converted into flats in the early 21st century, but it's origins are rather different.
It was originally built as the General Post Office for Southampton Docks.
All mail going out on ships from Southampton went through here, including 1,300 bags on board RMS Titanic - RMS stands for Royal Mail Steamer, indicating the vessel was licensed to carry Royal Mail post.
There were five postal staff working in the mail room on Titanic. They all perished as they tried to rescue as many post bags as possible.