People who live in nearby villages make their yearly pilgrimage as they walk up the slopes of the Popocatepetl volcano in Mexico, Wednesday, March 12, 2014. Every year on March 12, residents make their way up the volcano celebrate the day of Don Gregorio Chino Popocatepetl, as the volcano is known to them, with food, music, dance and fireworks. When the sun rises, hundreds of pilgrims head out from the towns of Santiago Xalintzintla, Tlamacas and San Nicolas de Los Ranchos in van and trucks to drive, then walk up the 17,886-foot (5,450-meter) volcano for their daylong celebration. (Photo by Eduardo Verdugo/AP Photo)

Britain's BASE jumper Sam Hardy lives up to his name after throwing himself off the top of the 335m-high Kuala Lumpur Tower during the KL Tower International Jump in Kuala Lumpur, Malaysia, Saturday, September 27, 2014. BASE stands for the places such jumpers usually jump from: buildings, antennas, spans (bridges) and earth (cliffs). (Photo by Lai Seng Sin/AP Photo)

BASE jumper Luke Denniss of Australia gestures as he dives in the air from the Kuala Lumpur Tower during the KL Tower International Jump in Kuala Lumpur, Malaysia, Saturday, September 27, 2014. BASE stands for the places such jumpers usually jump from: buildings, antennas, spans (bridges) and earth (cliffs). (Photo by Lai Seng Sin/AP Photo)

A student of the department for aritificial intelligence at the Freie Universitaet Berlin steers a converted Dodge minivan remotely with an iPhone during a demonstration at Tempelhof Airport on November 2, 2009 in Berlin, Germany. The car, whose design was led by professor Raul Rojas, is outfitted with a variety of laser sensors, GPS antennae and computers. (Photo by Sean Gallup/Getty Images)

A man takes a photo of a radio antenna that's part of the Atacama Large Milimeter Array Observatory on March 12, 2013 at Llano de Chajnantor, about 43 miles (70 kilometers) from San Pedro de Atacama, Chile. The $1.5 billion ALMA facility, which had its official inauguration on March 13, is considered the world's most expensive ground-based observatory. (Photo by Felipe Trueba/EPA)

The Haʻikū Stairs, also known as the Stairway to Heaven or Haʻikū Ladder, is a steep hiking trail on the island of Oʻahu. The trail began as a wooden ladder spiked to the cliff on the south side of the Haʻikū Valley. It was installed in 1942 to enable antenna cables to be strung from one side of the cliffs above Haʻikū Valley to the other. A building to provide a continuous communication link between Wahiawā and Haʻikū Valley Naval Radio Station was constructed at the peak of Puʻukeahiakahoe, elevation about 2,800 feet (850 m). The antennae transmitted very low frequency radio signals from a 200,000-watt Alexanderson alternator in the center of Haʻikū valley. The signals could reach US Navy submarines as far away as Tokyo Bay while the submarines were submerged.

Engineer Mikhail Venin works on an antenna for the Express AM8 new generation geostationary telecommunications heavy satellite at the large-sized transformed mechanical systems centre of the Reshetnev Information Satellite Systems company in the Siberian town of Zheleznogorsk April 2, 2014. The Express AM6 is a new generation satellite providing services including Russian governmental and presidential mobile communication, digital television and broadcasting, according to the Reshetnev company representatives. (Photo by Ilya Naymushin/Reuters)

Visitors enjoy a walk accross a suspension bridge for the pedestrians that is the longest such construction in the world shortly after its official opening at a mountain resort in Dolni Morava, Czech Republic, Friday, May 13, 2022. The 721-meter (2,365 feet) long bridge is built at the altitude of more than 1,100 meters above the sea level. It connects two ridges of the mountains up to 95 meters above a valley between them. (Photo by David W. Cerny/Reuters)