The Prime Minister visited the Department of Health offices at Skipton House in London Road on Tuesday to deliver a speech paying tribute to civil servants' work.
Mr Blair addressed hundreds of staff who gathered in the atrium of Skipton House next to Elephant and Castle Underground Station.
He talked about the "immense pressure and change" in the health service and told staff that the Department of Health is facing the biggest set of changes since the NHS was founded.
Skipton House was built in the early 1990s to accommodate civil servants previously based at nearby Alexander Fleming House, now known as Metro Central Heights.
Pictures of the visit can be seen on the 10 Downing Street website.