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 visitor takes a photo of a boulder plastic made of synthetic material called “To be in Limbo” hangs from the ceiling of the 20 meter high Jesuit Church in Vienna, Austria, Tuesday, November 25, 2014. The eight meter high, hollow and 700 kilogram heavy sculpture from the artists group Steinbrener/Dempf and Huber is supposed to symbolize faith and its threatening moments. The installation will remain until April 19, 2015 and then move to a church in Hamburg, Germany. (Photo by Ronald Zak/AP Photo)

With "Art Eggcident," Dutch artist Henk Hofstra demonstrates what it would look like if God threw giant eggs down at us. The eight large, sunny side up eggs measure almost 100 feet wide in diameter. The installation took place in Leeuwarden, a city in the north of the Netherlands.
"I hope it becomes a meeting place with room for art," says Henk. "Art that is different than a framed picture on the wall or a boring bronze sculpture. Art that shows us a different look, surprises us, or makes us angry or happy. Art that allows photographers to grab their cameras and arouses journalists. Art that evokes emotion, or provokes wild laughter."

Rope access technicians carry out maintenance service on wind turbines including repairs, blade inspections and cleaning in Izmir, Turkey on February 19, 2021. In Turkey, where investments in renewable energy has increased, there are wind tribunes over 3,500. (Photo by Mahmut Serdar Alakus/Anadolu Agency via Getty Images)

A man rides his bike along a controversial bike lane on Prospect Park West on August 17, 2011 in the Brooklyn borough of New York City. In what is being viewed as a victory for the Bloomberg administration, a judge on Tuesday dismissed an effort by Brooklyn residents to remove a bicycle lane installed by the city on Prospect Park West. Mayor Michael Bloomberg, along with his transportation commissioner, Janette Sadik-Khan, has attempted to make New York more bicycle and pedestrian friendly with numerous bike and pedestrian lanes around New York City. The effort has angered some in the city who see the lanes as adding to traffic, taking up parking spaces and a danger to pedestrians. (Photo by Spencer Platt/Getty Images)

A makeshift cart with containers is seen at a suspected drug tunnel under construction during a media tour by Mexican Army in Tijuana April 7, 2015. Mexican soldiers foiled the construction of a suspected drug tunnel underneath a house near the U.S. border, arresting nine people and impounding a truck used to clear debris, the Army said on Tuesday. Wired with lights, the tunnel was being built next to the Tijuana border crossing, south of San Diego, California, and near a Mexican air force installation as well as a regional federal police facility. (Photo by Reuters/Stringer)

The Museum of Feelings doesn't really have “exhibits" in the conventional sense; rather, visitors move from one themed alcove to another, five in total, each with its own distinctive aroma. The “Optimistic Room," bathed in vivid pink and purple light, is little more than a lightshow, with patrons using small reflective panels to bounce light around the room. Here: People interact in the “optimistic” room at the Museum of Feelings, a pop-up installation in New York, December 15, 2015. (Photo by Stephanie Keith/Reuters)

A humanoid robot named Kansei, meaning “sensibility” in Japanese, makes a facial expression depicting “happiness”, next to the word “Love” during a demonstration at a laboratory of Meiji University's Robot and Science Institute in Kawasaki, south of Tokyo in this June 4, 2007 file photo. Three-fourths of robot installations over the next decade are expected to be concentrated in four areas: transportation equipment, including the automotive sector; computer and electronic products; electrical equipment and machinery. Labor costs have climbed in countries such as China that have been popular for outsourcing production, while technological advances for robots allow them to be more flexible and perform more tasks. (Photo by Yuriko Nakao/Reuters)