The 2,199 transactions recorded last year were worth a combined €708.5 million, against 443 deals in 2008 worth a combined €160.9 million according to the data, from sector magazine 'Confidencial Imobiliário'.

The figures are from an analysis of Lisbon's 25 traditional neighbourhoods in the administrative parishes of Misericórdia, Santa Maria Maior and São Vicente, that includes information about sales of both buildings and parts of buildings.

In comments to Lusa the magazine's editor, Ricardo Guimarães, said that the growth in transactions in the city centre “is something of a reflection of the [fact that the] market for urban rehabilitation has become quite attractive for investors," while the previous dominant model of new builds on the city's outskirts has fallen away.

Urban rehabilitation, according to Guimarães, initially served as “a refuge for investors”, who viewed it as a lower-risk investment. In the meantime, there has been strong growth in tourism in Portugal's urban centres, with the growing popularity of "local lodging" in private apartments rather than hotels contributing greatly to the pace of investment.

Before the boom in rehabilitation, the magazine editor noted, the downtown area was seen as relatively unattractive and it was “an abandoned and deserted territory".

The year 2013 is when sales stopped falling and began to climb. In that year there were 1,340 transactions in the city centre, worth a combined €291 million, and the two years that followed consolidated that potential.

Last year the average price per square metre in the city centre ranges between €3,500 and €4,000.

Currently, Guimarães maintained, “the big buyer is the Portuguese [tourism] operator, the small Portuguese investor, from the point of view of local lodging," although foreign investors - above all French citizens - remain an important presence.