A better known real estate debacle is a sprawling development in Seseña, south of Madrid, one of Spain’s “ghost towns.” It sits in a desert surrounded by empty lots. Twelve whole blocks of brick apartment buildings, about 2,000 apartments, are empty; the rest, only partly occupied. Most of the ground floor commercial space is bricked up.

The boom and bust of Spain’s property sector is astonishing. Over a decade, land prices rose about 500 percent and developers built hundreds of thousands of units — about 800,000 in 2007 alone. Developments sprang up on the outskirts of cities ready to welcome many of the four million immigrants who had settled in Spain, many employed in construction.

At the same time, coastal villages were transformed into major residential areas for vacationing Spaniards and retired, sun-seeking northern Europeans. At its peak, the construction sector accounted for 12 percent of Spain’s gross domestic product, double the level in Britain or France.

But almost overnight, the market disappeared. Many immigrants went home. The national unemployment rate shot up to 20 percent. And the northern Europeans stopped buying, too. But government officials now say the worst is over, with housing prices down a modest 12.8 percent from the peak, according to the Bank of Spain.