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 radiation monitor indicates 114.00 microsieverts per hour near the building housing the plant's No. 4 reactor, center, and an under construction foundation, right, which will store the reactor's melted fuel rods at Tokyo Electric Power Co.'s tsunami-crippled Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Wednesday, March 6, 2013, ahead of the second anniversary of the March 11, 2011 tsunami and earthquake. Some 110,000 people living around the nuclear plant were evacuated after the massive March 11, 2011, earthquake and tsunami knocked out the plant's power and cooling systems, causing meltdowns in three reactors and spewing radiation into the surrounding air, soil and water. (Photo by Issei Kato/AP Photo/Pool)

South Korean workers are seen from a crane as they work on the 123rd floor during the framing completion ceremony of the 'Lotte World Tower' in Seoul, South Kora, 22 December 2015. The building's exterior was completed in a final height of 550 meters, and 123 floors. The ceremony came five years and two months after the construction of the building began and its opening will likely take place at the end of next year when the interior work is set to be completed, the South Korean Yonhap news agency reported. The building is the highest in South Korea and the fifth highest in the world, according to Yonhap. (Photo by Jeon Heon-Kyun/EPA)

Performers from the Joles ethnic group in Gambia prepare to perform with sharp blades which they say will demonstrate the magic powers of a spiritual water, that will make them immune to the cuts, during a campaign rally by incumbent President Yahya Jammeh, leader of the APRC (The Alliance for Patriotic Reorientation and Construction) in Bikama on November 24, 2016. As electoral favorite Jammeh seeks his fifth term in power, a two-week campaign period will come to an end next week ahead of the December 1st presidential election with political leaders canvassing in rural areas. (Photo by Marco Longari/AFP Photo)

Serra da Aboboreira Megalithic Set (Meninas do Crasto) on September 24, 2023 in Baiao, Portugal. Since 1978 that Serra da Aboboreira (Aboboreira Mountains) has been the scene of a systematic study of its archeological values, among which are the monuments known as megalithic. These are funerary monuments designing the landscape. These dolmens were constructed with stones (lithos) of medium or large dimensions (mega), which were laid in a, more or less, vertical position. Over these, it was still placed a lid, also of stone. These containers were covered by an artificial mound of earth and stones (dolmen). (Photo by Octavio Passos/Getty Images)

Twin brothers Keith (L) and Deano Stapleton (R) interact with one another as people gather to witness the winter solstice on December 21, 2022 in Newgrange, Ireland. Crowds are gathering at Newgrange in Co Meath, this morning for the winter solstice – the astronomical phenomenon that marks the shortest day and the longest night of the year. Newgrange is a Stone Age (Neolithic) monument in the Boyne Valley, County Meath, it is the jewel in the crown of Ireland's Ancient East and was constructed approximately 5,200 years ago (3,200 B.C.) which makes it older than Stonehenge and the Great Pyramids of Giza. (Photo by Charles McQuillan/Getty Images)

A participant from Indonesia waits to perform a dance during the last day of World Culture Festival on the banks of the river Yamuna in New Delhi, India, March 13, 2016. The festival opened on the banks of the Yamuna River in the Indian capital Friday despite concerns the sprawling construction of roads, ramps and pontoon bridges would irreparably damage the river's floodplains. (Photo by Adnan Abidi/Reuters)

Malian workers haul out a boat they use to carry sand collected from the river bed during a routine maintenance on October 7, 2018, in the port of Bamako. Increasing construction in the Malian capital has boosted the demand for bricks made out of high-quality Niger River sand. (Photo by Michele Cattani/AFP Photo)