You'll need a headlamp, a tight waistline and no fear of the dark in order to enjoy one of the most extreme, yet lesser known, archaeological wonders of the Holy Land.
Still, even with the proper equipment and intestinal fortitude, it is easy to lose your cool when crawling through the expansive ancient tunnel systems dug by Jewish rebels to fight the Roman Empire.
The hundreds of hideouts, ranging from just a few meters deep to seemingly unending labyrinths, are popular among Israeli archaeologists and adventurists. But the subterranean mazes, which date back as early as the first century BC, are virtually unknown to foreigners.
Even if you go looking for them, as designed, they are easy to miss.
The systems were often reached through trap doors in Jewish villages, some of which are now archaeological sites, others have been completely destroyed. Today, they may be no more than an indistinct, shoulder-width opening in the ground or hillside.
You may have to crawl, even slither, for a few minutes through a pitch-black burrow -- too cramped for a fully armed Roman legionary. Turns can be so tight you may have to back up to a spot where you can flip from head to feet first in order to continue.
Your headlamp will illuminate niches where oil lamps once lay and other carvings in the rocks. And suddenly you may come to an expansive columbarium, with hundreds of holes in the wall once used to raise pigeons, or perhaps a decorated storage room.
From there, the system may tunnel off in different directions, giving the sense of how the Jewish rebels lived and fought during two revolts against the Romans -- the first around the time the great temple was destroyed in Jerusalem in 70 AD, and one decades later under legendary leader Bar Kochba.
"Crawling inside a hiding complex is a thrill. We always expect the unexpected," said Amos Frumkin, a professor at the Geography Department at the Hebrew University of Jerusalem who heads the school's Cave Research Unit.
For decades he and his team have explored and mapped newly discovered systems, passing many days each year underground. They have found ancient weapons, trap doors and olive presses during their surveys. Their findings are published in an obscure journal called "Niqrot Zurim", or "Caverns in the Rocks".
The foothills of Jerusalem around the ancient city of Beit Guvrin are like an ant farm and best tell the story of the guerilla tactics used in the Bar Kochba rebellion. The rebel strategy worked for a while, but the Romans eventually defeated them.
Earlier caves have been found farther north in the Galilee, where team members were called to explore a tunnel system found just a few months ago. Archaeologists had uncovered what they thought was a standard, eight-meter-deep water cistern, but later noticed it had narrow crawl spaces shooting off its base.
The team rappelled to the lower level, the first people in 2,000 years to tread there. With a metal detector and laser measurer they spent hours mapping just a fraction of the tunnels.
Researchers have also mapped many of the nearby cavern hideouts that dot the cliff side of Mount Arbel overlooking the Sea of Galilee. Roman historian Josephus described in his writings how King Herod lowered his men in chests from the cliff to the cave openings and, using fire, overtook the rebels.
It is easy to lose your way in these underground mazes. Only a handful are well-marked and maintained, and it is best to hire a guide to take you around. And with proper climbing equipment, the extremely brave and experienced can repel even deeper if they come upon massive subterranean cisterns and chambers.
"These tunnels are an amazing secret that tourists unfortunately don't know about," said veteran guide Asael Lavi. "It's possible to spend an entire day or two crawling in the different systems and experience the fear, grief and even excitement that the rebels must have felt."
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