Cordoba, Spain (CNN) The fortress town of Zahara de la Sierra in southern Spain is used to fending off enemies. The Moors and Christians fought over it in medieval times, and it was sacked by the French in 1812. Now its formidable position high above the Andalusian countryside has suddenly become an invaluable asset once more.

On March 14, Zahara cut itself off from the outside world as a dangerous coronavirus spread its tentacles across Spain . The mayor, 40-year-old Santiago Galván, decided to block all but one of the town's five entrances. Galván acted the day that Spain's "state of alarm" came into force.

Since then, the country has recorded more than 100,000 cases and 10,000 deaths, according to Johns Hopkins University figures.

On March 14, Zahara de la Sierra cut itself off from the world as the coronavirus spread through Spain.

In Zahara, however, there has not been a single recorded case of Covid-19 among its 1,400 inhabitants. "It has been more than two weeks, and I think that's a good sign," Galván told CNN.

The mayor's drastic steps have the full support of the townspeople, and especially the elderly. Nearly a quarter of Zahara's inhabitants are older than 65; there are more than 30 residents in an old people's home. Towns and villages nearby have seen infections and several coronavirus fatalities.

Zahara's white houses and narrow streets cling to the steep hillside, looking up at medieval fortifications and down towards a reservoir and rolling olive groves. An hour from Seville by car, it's a popular destination for visitors from around the world. Galván says that in the first few days, they had to turn away French and German tourists who were unaware of the local government's measures.

Four of the town's entrances were blocked, leaving just one, which has a manned checkpoint where vehicles are sprayed with a mix of bleach and water.

The checkpoint on the one access road is run by a single police officer. Two men dressed in the protective clothing normally used for spraying the olive groves wash vehicles that come through with a mix of bleach and water. The vehicles even have to pass through a sort of sheep-dip to ensure their tires are disinfected.

"There is no car that comes through the checkpoint that's not disinfected," says Galván.

The mayor admits that such measures could be anywhere from 20% to 80% effective, but says it's all about reassurance. "We have managed to give tranquility to our neighbors," he says. "They know no one 'unknown' can come in."

Similar sanitation precautions have been introduced inside Zahara. "Every Monday and Thursday at 5:30 p.m. a group of around 10 people are out in the streets to disinfect the town, all the streets, plazas and outside homes," Galván says.

One of them is local farmer Antonio Atienza, whose tractor trundles through the town spraying the streets.

A local business is paying two women to make grocery and medical deliveries to reduce the number of people out on the streets, especially those most vulnerable to contracting the virus. They work about 11 hours a day and their order book is growing.

One of them, 48-year-old Auxi Rascon, says the response from other citizens has been wonderful.

A group of volunteers and town workers clean and disinfect the streets.

"They are very happy, because they don't need to go out, they feel protected and feel confident," she says. Rascon is also proud of the town's swift response. "They took the right measures at the right moment, and now we are seeing the results," she told CNN by phone.

Besides organizing the delivery service, the Zaharilla women's association looks after the elderly who can't cook for themselves (by leaving food at their front doors) and arranges basic repairs for them. A Facebook page created for older residents has started a drive to get their old photographs published online. Luisa Ruiz Luna, who started the initiative, says it's taken off, and is "a nice way for Zaharenos who live abroad to interact with us, apart from exercising the memory."

The town has also outfitted two cars with music and lights, "so kids can come to their balconies and enjoy them," Galván says.

Zahara de la Sierra's Mayor Santiago Galván acted on the same day that Spain's "state of alarm" came into force.

The economic lifeblood of hundreds of small Spanish towns like Zahara is provided by family-run businesses and "autonomos" -- the self-employed. So the town council has dipped into its contingency fund to cover the costs of electricity, water and taxes for local businesses during the national state of emergency. Bars and restaurants reliant on tourism -- there are 19 such establishments in Zahara -- would otherwise go to the wall.

For Galván, it's more than financial aid. It's about preserving Zahara as a community. His father was born in the town. But the mayor knows that in the end, Zahara will need help from Madrid or the regional government if the national confinement continues.

"We will need a sort of financial lung if this goes on," Galván told CNN.

Like millions of Spaniards, he scrutinizes the Ministry of Health's daily Covid-19 bulletins, hoping that like the sieges of Zahara in centuries past, this too shall pass.