The Mysterious Hochbunkers of Europe

You can find them all over Germany and Austria - strange fortified structures of heavy concrete. Few or no windows. They're located in odd places, off by themselves in the woods, or surrounded by modern glass and steel office buildings. They don't seem to fit their surroundings and it's not clear what they're for. They're hochbunkers, or "high bunkers," originally built by the Nazis as above-ground bomb shelters during World War II.

The concept of a bomb shelter is familiar enough, but they're usually built underground. During the cold war, both the Americans and the Russians built massive underground complexes in case of nuclear attack. During World War II, the English used the London Underground (in addition, some say, to building huge subterranean military complexes whose existence still isn't confirmed by the government.)

But the Germans mostly built their shelters above ground. It was cheaper to build towers than to excavate underground shelters and so the Germans built them everywhere. Many were massive bunkers with meter-thick concrete walls and flat roofs topped with searchlights and anti-aircraft guns. Others were made to look vaguely like medieval castles.

But some of the most distinctive were the "Winkel Towers," named for their inventor, architect Leo Winkel. Winkel's design called for a round tower, with gently sloping sides and a conical top. The idea was that the shape of the building would deflect falling bombs, causing them to explode only at the base, which would have extra thick reinforcement.

With several floors stacked up inside, Winkel's towers could hold plenty of people. They were easy to build, and they didn't take up much space. This both made them harder to hit from the air and meant they could be built on almost any odd corner of unused land. The Germans built nearly 100 Winkel Towers, near railroad yards, industrial complexes and other places they expected to be bombed. The towers are hard to miss, looking remarkably like huge concrete missiles emerging from beneath the ground.

It's actually debatable whether Winkel's design worked as intended. Without modern precision bombs, World War II bombing tactics called for blanketing an area with huge numbers of bombs and hoping for the best. And the targets were the factories and rail yards. It's not as though allied bombardiers would be aiming directly at the bomb shelters. And there is one reported incident in which a Winkel Tower was struck directly by an allied bomb. The bomb penetrated the roof and killed five people inside.

Nonetheless, most of the hochbunkers survived the war and are still in place today. Why weren't they destroyed after the war like so many other reminders of the Nazis?

Well, not for lack of trying. But remember these structures were specifically designed to survive massive aerial bombardment. Their whole purpose was to resist demolition. There was an effort to destroy one of the six massive flak towers outside Vienna. Local authorities eventually gave up after their best efforts to destroy the structure only managed to put a crack in one wall.

Stuck with the hochbunkers, locals made the best of them. Some of the more "ordinary" looking ones were converted into storage space, or used as additional space for hospitals or schools. But the Winkel Towers proved harder to adapt to civilian life. Their odd shapes and interior layouts made them more or less useless as anything but bomb shelters.

So they're still there today, and townspeople just build around them as best they can. A few have been converted into local museums or bus stops. Others have been painted in happy colors and patterns - polka dots, for example. Others are simply ignored. Overgrown with foliage or sitting in the middle of suburban industrial parks, they still lurk in the corner of the eye, a reminder of an unpleasant time.