Empty promises abound in the capital, but who wants them?

Some 421 buildings lie empty in central Madrid - the area bounded by the M30 ring road - along with a further 573 vacant lots. At the same time, City Hall is currently processing 1,496 applications for construction permits. The potential value of the empty properties and vacant lots is estimated at around 12 billion euros, according to a survey carried out by the San Pablo CEU University in Madrid.

How did this failure to utilize valuable real estate come about? The answers are varied. Twenty-two years ago, a convent in the working class Tetuán neighborhood, in the northwest of the city, was demolished. Today, the site remains undeveloped. Five years before it was knocked down, the early 20th century gothic revival complex had been acquired by the state, with the intention of maintaining the façade and building office space within. Residents said that they wanted a sports and leisure facility. Attempts since then to auction the land have come to nothing.

The report lays most of the blame for the empty holes that litter the center of Madrid on the financial crisis, and the construction boom that precipitated it. Although in the case of the demolished convent, it is City Hall that has failed to make use of valuable land and to meet the needs of local people.

Our aim is to highlight the potential in the center of Madrid"

"Our aim is to highlight the potential that still remains in the center of Madrid," says Carlos Lahoz, one of the four authors of the study. "No major investments would be necessary in the areas we have looked at, because they already have access to all basic services and utilities," he adds.

Tetuán and nearby Moncloa have half of the unused land, although the single largest area of empty plots is to be found in Arganzuela, in the southwest of the city. In total, says the CEU San Pablo University report, there are more than 630,000 square meters of vacant land, equivalent to half of the capital's Retiro park. The report estimates that if the land were to be used, it would be worth around 6.5 billion euros. Part of that potential was lost, says the report, when Madrid failed in its third consecutive attempt to host the Olympics.

There are more than 630,000 square meters of vacant land in the capital

The team also says that Madrid is failing to make the most of some of the city's most emblematic properties, such as the building that stands on the corner of María de Molina and the Castellana boulevard. Back in 2007, at the height of the property boom, this was being advertised as the capital's most luxurious apartment block. The dozen or so properties within belonged to a developer called Martinsa Fadesa, which later went belly up. Six years on, of the total of 26 apartments available for rent or purchase, only one is occupied.

The building is in good shape, and the presence of flowers and plants on its balconies suggests that it is filled with tenants. Most of the more than 400 other buildings either empty or minimally occupied are more modest, although another spectacular example of waste is the Edificio de España, at the bottom of Gran Vía, which has been empty for the last decade.

In the nearby Plaza del Carmen, a former cinema sits abandoned, slowly rotting while it awaits being put to a new use; another victim of the collapse of the capital's property market, and another indication of Madrid's failure to utilize its existing infrastructure.