The biggest lens you'll never see

The Zeiss Apo Sonnar T* was designed by Carl Zeiss to be the world's largest nonmilitary camera lens. The 1,700mm lens weighs more than 550 pounds, is larger than a refrigerator, and gives a medium-format camera a telephoto factor of almost 29X. Don't expect to actually see it in the wild anytime soon, though; the Apo Sonnar T* is a special project from Carl Zeiss and costs as much as a small house.

Source: DP Review via Gizmodo