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.

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)

Sad woman standing near car with scratch on parking and talking by the phone. (Photo by Vera Petrunina/Getty Images)

A model poses in front of phone boxes for a photographer in London, United Kingdom on Friday, October 1, 2021. (Photo by Frank Augstein/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)

American singer and model Ciara in the second decade of March 2023 makes a very important phone call. (Photo by ciara/Instagram)

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)

Woman on phone in hotel room. (Photo by DreamPictures/Getty Images)