The Grand Canyon Skywalk is a transparent horseshoe-shaped cantilever bridge and tourist attraction in Arizona near the Colorado River on the edge of a side canyon in the Grand Canyon West area of the main canyon. USGS topographic maps show the elevation at the Skywalk's location as 4,770 ft (1,450 m) and the elevation of the Colorado River in the base of the canyon as 1,160 ft (350 m), and they show that the height of the precisely vertical drop directly under the skywalk is between 500 ft (150 m) and 800 ft (240 m).

Martina Maggio, Alice D'Amato, Lara Mori, Asia D'Amato, and Vanessa Ferrari of Team Italy pose in front of the rings during Women's Qualification on day two of the Tokyo 2020 Olympic Games at Ariake Gymnastics Centre on July 25, 2021 in Tokyo, Japan. (Photo by Mike Blake/Reuters)

Cordwood construction is a method of natural building that originated roughly one thousand years ago in Greece and Siberia. This method involves using pieces of wood that slightly protrude from the mortar, giving the walls an attractive appearance. Usually, the walls are made 12 to 24 inches thick. However, in some parts of Canada, the walls can be as thick as 36 inches. This method appeals to many people due to its ease of construction economy of resources. Cordwood Construction can be separated into two main types: mortar-insulation-mortar (M-I-M) and Throughwall. M-I-M is a more preferable and widely used choice as it allows for better insulating properties.

Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

Danila Shmelev, an artist from Moscow, Russia, works on a 3-D picture in Dubai, United Arab Emirates, Monday, February 27, 2017. Artists who focus on 3-D pictures have gathered in Dubai for the Dubai Canvas 3-D Art Festival, which runs from March 1 through March 7. (Photo by Jon Gambrell/AP Photo)

Rep. Jason Crow, D-Colo., comforts Rep. Susan Wild, D-Pa., while taking cover as protesters disrupt the joint session of Congress to certify the Electoral College vote on Wednesday, January 6, 2021. (Photo By Tom Williams/CQ-Roll Call, Inc via Getty Images)

Young female Ibex on the fork of Disteis (2,200 m), near the top of the Jof di Montasio (Friuli, Italy). (Photo by Stefano Zocca)