Transamerica Pyramid, San Francisco

As much a trademark of the city's skyline as the Golden Gate Bridge, this 853-foot high masterpiece, the tallest office tower in the city, is headquarters to some of San Francisco's most powerful companies. Unfortunately, the elevator, which ascends to the building's uppermost heights, is no longer open to the public. Fortunately, rooftop video cameras allow visitors to "virtually see" the bird's-eye view from the comfort of the lobby. Outside, a man-made Redwood Park offers a welcome green oasis within the concrete jungle.