A decade after Spain's property bubble burst, dozens of vacant apartments in Madrid and Barcelona city centers have turned into "drug flats," to the dismay of local residents who complain of abandoned syringes and frequent brawls.
"You don't live anymore. You are more afraid at home than outside," said Begona Sebastian, a 51-year-old accountant whose building was one of the first in Lavapies, a district in the centre of Madrid, to have a "narcopiso," or drug flat, where people come to buy and consume drugs.
For three years, dealers sold hashish and cocaine in the apartment below her own, which had been seized by a bank from a heavily indebted family.
In mid-2016, she managed to have the squatters evicted and the door of the flat walled up to avoid it from being illegally occupied again by drug dealers.
The building was infested with bedbugs, and the constant coming and going of drug buyers, combined with the fear that the squatters could trigger an explosion with the gas cylinders they used for heating, caused her to lose sleep.
"You end up crying," said Sebastian, a brunette with a round face, as she passed by another drug flat that has since sprung up in Lavapies, an old district of steep and narrow streets that has a high immigrant population.
She knows by heart the addresses of each drug flat and has learned how to recognise them from the outside due to their broken doors and windows boarded up with cardboard.
Other neighborhoods in Spanish cities, such as the working class Puente de Vallecas district in southern Madrid and El Raval in the centre of Barcelona, have seen an explosion in the number of drug flats in recent years, sparking street protests by locals.
Some have taken to hanging red flags from their windows to draw attention to the problem.
Figures on how many empty flats have been taken over by drug dealers are hard to come by.
The interior ministry does not have national statistics on drug flats and refers any questions to local authorities.
In the Madrid region, national police say they have dismantled 105 "narco flats" in 2017, and made 314 arrests.
Catalan police said that by early this month 17 flats had been searched so far this year in connection with drug trafficking and 34 people arrested.
The authorities blame the rise in drug flats on the sharp economic downturn that followed the collapse of a decade-long building boom in 2008 causing tens of thousands of families to be evicted from their homes.
The empty flats they left behind often belong to banks or investment funds, which can not sell them without making a huge loss, so they leave them empty while waiting for property values to rise.
"El Raval is one of the areas most affected by speculation, with buildings in a deplorable state of conservation, which facilitates occupations," said Gala Pin, the local Barcelona city councilwoman.
"Mafias occupy the apartments, then they sell drugs there, or they install people who sell for them," a police source told AFP.
Traffickers take advantage of the fact that it is only possible to evict squatters with a court order, which can take months to obtain, the source added.
"They started by selling a lot of hashish, then they saw that there was also a demand for cocaine and sometimes even heroin."
The opioid epidemic in the United States has revived bad memories in Spain of its own devastating heroin crisis of the 1980s.
"In my generation, everyone has lost friends because of heroin, and we do not want it to start again," said Manolo Osuna, 54, a postman in Lavapies.
In Barcelona, Carlos, a spokesman for a neighborhood association in El Raval who declined to give his last name because he fears the drug traffickers, said the "streets are full of people who look like zombies".
"The stairs are soiled by blood, feces, urine, they leave behind syringes," said Carlos, who lived next to a building, which until October was a key drug sales point in Barcelona.
Police and social workers say drug trafficking is moving from marginal areas on the outskirts of cities where the authorities have increased anti-drug operations, to city centers.
"Depending on where police pressure is, traffic is moving," said Josep Rovira, the spokesman for the Catalan Federation of Drug Addiction.
Barcelona city hall, led by a leftist former housing activist, tries to convince the owners of empty flats to rent them.
Madrid's left-wing city hall has boosted the number of municipal police to fight the problem and said it will install security cameras on streets with drug flats.
Associations that work with drug addicts have called for the government to do more to care for drug addicts and reduce the risk that they will suffer an overdose.
"It's a reality that will always exist," said Rovira.