Many reasons why the Portuguese real estate market has been very active in recent years.
First, it is the private capital that flows into the state.
High quality of life, tax benefits for foreigners, Golden Visa program, preferred destination for relocation or buying a kit house.
All these and more attract private investments which push the prices up and of course in turn increase the rate of investment in new projects by large local or foreign companies.

Second, Portugal is experiencing an unprecedented tourism boom. The big cities Lisbon, the capital, has long been listed on the world tourism map. In southern Portugal, the Algarve region attracts millions every year to its long beaches. And when old buildings are turned into hotels and apartments are used to accommodate tourists, there is a shortage of residential apartments. The demand is great and the entrepreneurs are not expected to close the gap between demand and supply soon.

Third, after years of stagnation there is a revival of entrepreneurship. Whether because of suffocating bureaucracy or tenant protection laws that prevented real estate ventures from operating, whether because of the recent economic crisis or over-reliance on the European Union, over the years there have been various reasons for stagnation. Today it is clear that the trend has completely changed and the market is growing rapidly.

See an article from Calcalist:

https://www.calcalist.co.il/world/articles/0,7340,L-3747929,00.html