A worker prepares the “Cutter Head” of the Port Tunnel boring machine for attachment to the tunneling machine on September 1, 2011 in Miami, Florida. The $45 million machine is longer than a football field and about as tall as a four-story building and it will carve the twin tunnels connecting Watson Island and Dodge Island. The the new $1 billion Port of Miami tunnel is expected to be completed in May of 2014. (Photo by Joe Raedle/Getty Images)

Sunset is seen through smoke from the Wallow fire June 8, 2011 in Springerville, Arizona. Hundreds of thousands of acres have burned in eastern Arizona prompting evacuations by residents. Smoke loomed over the twin towns of Eager and Springerville, home to about 7,000 people north of the fire. (Photo by Eric Thayer/Getty Images)

Construction continues on One World Trade Center (TALLEST BUILDING AT LOWER LEFT) as the memorial footprints of the twin towers are seen (BOTTOM C) on August 12, 2011 in New York City. Upon completion, One World Trade Center will be New York's tallest skyscraper, topping out at a symbolic 1,776 feet, with 3 million square feet of office space. More than 2,700 people were killed when al-Qaeda terrorists hijacked U.S. passenger jets and flew them into the twin towers of the World Trade Center on September 11, 2001. Nearly ten years after the crippling attacks on Lower Manhattan, business, tourism and new construction like One World Trade Center have rejuvenated the formerly devastated cityscape.(Photo by Mario Tama/Getty Images)

Lindsay Knutson plays in the heavy snow with her family dog, Aspen, and daughter Flora Bejblik, 4, cq, as her husband Bob Bejblik, rear left, shovels, Tuesday, March 5, 2013 in southwest Minneapolis. The National Weather Service predicted a two-day snow total of 8 to 12 inches for much of southeastern and east-central Minnesota, including the Twin Cities. (Photo by Elizabeth Flores/AP Photo/The Star Tribune)

A woman wearing a scarf to cover her face looks on as she waits for a passenger bus on a smoggy morning in New Delhi, India, November 8, 2017. The Great Smog of Delhi is an ongoing severe air-pollution event in New Delhi and adjoining areas in the National Capital Territory of India, in November 2017. Air pollution at this time peaked on both PM 2.5 and PM 10 levels. It has been reported as one of the worst levels of air quality in Delhi since 1999. (Photo by Saumya Khandelwal/Reuters)

Gorbea Natural Park is a protected area located between the provinces of Alava and Vizcaya in the Basque Country of northern Spain. Gorbea takes its name from its highest peak, the Gorbea (or Gorbeia) at 1,482 metres (4,862 ft) above sea level.

The National September 11 Memorial & Museum (branded as 9/11 Memorial and 9/11 Memorial Museum) is the principal memorial and museum commemorating the September 11 attacks of 2001, which killed nearly 3,000 people, and the World Trade Center bombing of 1993, which killed six. The memorial is located at the World Trade Center site, on the former location of the Twin Towers, which were destroyed during the attacks. The World Trade Center Memorial Foundation was renamed the National September 11 Memorial & Museum at the World Trade Center in 2007.

Tourists from Holland peak through a crack in a still-existing portion of the Berlin Wall at the main memorial to the Wall in Bernauer Strasse on the 22nd anniversary of the fall of the Wall on November 9, 2011 in Berlin, Germany. The Berlin Wall, erected by the communist authorities of then East Germany in 1961, divided the city and prevented East Germans from travelling west until the collapse of the Eastern Bloc in 1989. (Photo by Sean Gallup/Getty Images)