Can the world get enough vertical drop views over familiar destinations?
It seems not.
After the Grand Canyon, Chicago's Willis Tower and, more recently, the Eiffel Tower in Paris installed glass walkways offering vertigo-inducing perspectives, London has followed suit.
The city's Tower Bridge, a 120-year-old crossing over the River Thames, is the latest structure to join the club with a see-through walkway that allows visitors to gaze down from 42 meters (138 feet).
The walkway, the first structural alteration to the bridge since 1980s, passes over the west side of the bridge. A second walkway on the east side is to open December 1.
During construction, it was known as the "wow project" -- and with good reason.
Visitors to the attraction can look down to see London's red buses and black cabs zip beneath their feet or gaze at the bridge's impressive steel latticework.
There are also spectacular views over the city's skyline.
If they're lucky, or plan in advance, visitors will also get to watch the bridge being raised to allow tall shipping to pass beneath.