Catwalks hang over a section of the newly constructed eastern span of the San Francisco-Oakland Bay Bridge during a media tour of the self-anchored suspension span tower on August 29, 2011 in Oakland, California. Contruction crews have erected twelve foot wide catwalks that connect to the San Francisco-Oakland Bay Bridge self-anchored suspension span's tower and crews will begin to lay the nearly one mile of main cable beginning in early 2012. The bridge has been under constrution since 2002 with an estimated price tag of $6.3 billion and will have the world's tallest Self-Anchored Suspension (SAS) tower once completed. (Photo by Justin Sullivan/Getty Images)

French artist Olivier Grossetête used three enormous helium balloons to float a rope bridge over a lake in Tatton Park, a historic estate in north-west England.

DJI Phantom 3 Severe Crash - Train Bridge

Yolanthe Cabau attends amfAR MILANO 2011 at La Permanente on September 23, 2011 in Milan, Italy. (Photo by Vittorio Zunino Celotto/Getty Images for amfAR)

Bullfighter Julian Lopez “El Juli” of Spain performs during the second bullfight of the 2011 season at the Monumental bullring on July 10, 2011 in Barcelona, Spain. This will be the last year for Bull fighting at the Monumental bullring as the parliament of Catalonia has voted to ban bullfighting as of January 1, 2012. (Photo by David Ramos/Getty Images)

Participants enjoy mud during the 14th Annual Boryeong Mud Festival at Daecheon Beach on July 16, 2011 in Boryeong, South Korea. The mud, which is believed to have beneficial effects on the skin due to its mineral content, is sourced from mud flats near Boryeong and transported to the beach by truck. (Photo by Chung Sung-Jun/Getty Images)

Miss Venezuela Ivian Sarcos receives her Miss World 2012 sash from Miss World 2011 by Miss World 2010, Alexandria Mills (R) in the Miss world 2011 World Final on November 6, 2011 in London, England. (Photo by Jeremy O'Donnell/Getty Images)

The original costumes for Star Wars character Darth Vader stand on display at “Star Wars: The Exhibition” at County hall on May 04, 2007 in London, England. (Photo by MJ Kim/Getty Images)