Skywalks in Jasper National Park (Canada), in Arizona over the Grand Canyon (USA), and in Tianmen Mountain (China), have what in common?
What is the dam in the Black Canyon of the Colorado River on the border between the US states of Arizona and Nevada that was completed in 1935?
In June 2009, Canada announced plans to extend which national park from 4,800 square kilometres to 30,000 square kilometres to help protect the habitat of grizzly bear, caribou and other species?
