Jews from the diaspora have been snapping up prime Israeli real estate for years. Now, however, they are starting to buy underground - in a network of catacombs carved out of the rocky soil below Jerusalem's largest cemetery.

The $50 million building project, mostly funded by pre-orders from Jews abroad, will include 22,000 burial plots on three levels, as well as elevators, ambient lighting and decorated stonework.

Construction kicked off a few months ago on the Har Hamenuchot hilltop in West Jerusalem, which is best known as the burial site of the four French Jews killed in the terror attack in Paris in January. Around 150,000 people are buried above ground at the cemetery.

Using cutting-edge technology, Israel is hoping to meet the demand for the increasing number of people wishing to be laid to rest in a progressively crowded Holy Land.

While the initiative is the first of its kind in the modern era, experts such as Hananya Shachar, director of the Jerusalem Jewish Community Burial Society, say it may soon become the only option, given that above-ground cemeteries are almost full.

"We need our land for the living and not for the dead. Now we've got the drilling equipment, the know-how and the means, so we said, 'Let's go for it'," he told the Washington Post.

Built in 1951, Har Hamenuchot has continually expanded in size to become Israel's largest cemetery. Prior to its creation, the Mount of Olives in the city's east was the country's main burial ground.