Using Boston as an example again, let’s cautiously assume that the city could earn a 3% yield on its commercial assets with more professional and politically independent management. A modest yield of 3% on a portfolio worth $55 billion would amount to an income exceeding its current total revenues, and many times more than Boston’s current capital plan. Even with a modest yield, Boston could more than double its infrastructure investments.

Boston is by no means exceptional. On the contrary, its approach to historical valuation is shared by cities worldwide. As a result, public wealth is trapped in real estate and other non-optimized commercial assets.

The best way forward would be to consolidate publicly owned assets in a common investment vehicle that Stefan Fölster and I have called an “urban wealth fund.” The fund would be managed at arm’s length in a transparent, accountable manner, guided by a city mandate but directed by a dedicated professional staff to keep it free from political influence.

This sounds challenging, but it canbe done. Hamburg’s HafenCity GmbH, and parts of Copenhagen that were revitalized by the City & Port Development Company, are just two examples of urban areas that have used this type of development mechanism. These efforts have not only increased the amount of residential housing; they have also funded vital infrastructure such as the Copenhagen Metro, schools, and universities. In Hamburg, the recently opened Elbe Symphony Hallwas also funded via a government-owned holding company.

Managing city assets better would help local leaders boost their economies, finance social and economic infrastructure, and develop strategies for vibrant and innovative mixed-use projects. Better management of city assets would also help cover the costs of required maintenance without competing with government budgets, leaving more for spending on health care, education, and other social initiatives.

As urban populations grow, city planners must become more adept at budgeting for the long term. And there is no better way to do that than by using the assets that are already in place.