[SunkenCiv]

Update (?):

Photo: Lost Crusaders' Tunnels Found Near Palace on Malta -- Discovered in February 2009 in the capital of the Mediterranean island nation of Malta, this tunnel is thought to be part of a centuries-old underground water system built by the Knights of Malta.

Established in the 11th century, the military order was a key fighting force in the Crusades, a series of Christian military campaigns that originally had the goal of capturing Jerusalem. The Knights of Malta ruled the island from 1530 to 1798.

Photograph courtesy Claude Borg of the Valletta Rehabilitation Project

[Ramius]

Wow... that stonework is in great shape.

[Lady Jag]

Card, have seen this?

[wildbill]

There was a TV show on Discovery or PBS —or maybe National Geographic—about a huge long tunnel in Asia Minor (Modern Turkey) I saw not long ago.

Built by Roman army troops it brought water over a very long distance through a mountain or something.

Then there are the waterworks in Spain, where the largest Roman gold mine was mined by hydraulic pressure. See

www.typicallyspanish.com/news/publish/article_20790.shtml -

Their engineers used a technique known to Pliny the Elder as ‘Ruina Montium,’ literally ‘destroy the mountain,’ using the force of water to exploit the rich mineral resources of the area. It was an amazing feat of engineering which led Pliny to say when he first arrived there, ‘What happens in Las Médulas is far beyond the work of giants.’
The Roman engineers constructed a vast hydraulics network to channel water from as far away as 100 kilometres up the face of the mountains. There, the water was stored in large reservoirs until the sluice was opened to wash down the soil in a sudden rush of water – either along trenches or grooves cut into the mountain side - bringing with it the gold.
Another technique was applied within the mountains, where thousands of men dug galleries and channels out of the rock. There was only one exit – where the water was let in to bring down the mountain and release the gold-bearing rock as the enormous pressure caused the mountain to explode.

[AppyPappy]

They used a lot of these during WW2 as bomb shelters

[decal]

“The Knights of Malta ruled the island from 1530 to 1798.”

Now they rule a building in Rome - The Sovereign and Military Order of Malta has been called the smallest country in the world.

http://www.orderofmalta.org/english