The issue of public-owned land which no longer receives its official use and whose sale could help a governmental economic initiative is a recurrent government proposal in many countries, albeit under different approaches. This covers old barracks, or rail yards, or even airports that no longer serve their original purpose, but often have been surrounded by the city in ways not originally planned, and so gained a relevant real estate value. Obsolescence becomes the driver for urban planning, combined with the need to raise money hard to get in other parts. This week there has been an announcement that the French government intends to go that way to boost social housing in a moment of economic crisis through a bill for the”mobilisation générale pour la construction de logements” (general mobilization to build housing).

The issues at stake in such operations are, among others:

• Functional obsolescence of a given public infrastructure in itself does not make the land fit for housing building (think of an obsolete rail yard 10 km from any populated place), or can have such costs as to need a broader project (e.g., contaminated soils have remediation cost that would make any housing operation extremely expensive)
• Existing public land could have a geometry needing the inclusion in the project of non public land, and this could make the operational management much more complex, either through compulsory purchase or a mixed private – public operation. When land from different government entities or levels must be assembled for the project, the complexity is also present.
• If building housing is the goal of the project, in some cases it would make more sense to sell the land to build the new social housing in other areas. No doubt, there is an aim to make socially inclusive neighborhoods, but it could be better to create activity spaces that could create an employment basis, just to name a possible outcome. In some countries there are legal limitations to the future use of any public land in transformation projects, putting social housing first,but the results are not always better.
• Who is the real owner of the public land? in some cases it may have been acquired through an eminent domain clause, meaning that the use (e.g. a rail line) is declared of public utility, forcing the previous owner to sell. In some countries the previous owner can ask to receive the land back when the reason by which the eminent domain clause was applied disappears.