Measuring just five feet at its widest point, the ultra-thin home was unveiled in the Polish capital of Warsaw on Sunday, October 21, 2012. Photo: The Keret House is squeezed into the space between two apartment buildings in Warsaw. There's a four-inch gap between the apartment buildings to either side. A perforated steel facade was used to allow in more light. (Photo by Andrea Meichsner/The New York Times)

Indian passengers travel on a local train in New Delhi, India, October 2017. Constructed in 1975 to bypass the crowded and passenger-heavy Old Delhi, New Delhi and Hazrat Nizamuddin railway stations, the railway line once used to be the lifeline of the capital. (Photo by Ankur Dutta/Barcroft Media)

Shokyo Miura, a Buddhist monk and one of the on-site priests, poses for pictures outside Tera Cafe in Tokyo, Japan, April 1, 2016. At first glance, the cafe, which also serves alcohol, looks like any other except for an altar next to the countertop bar with a Buddha statue set against a gold backdrop. The menu confirms this is something different. It lists classes for 1,500 yen ($14) in weaving prayer beads, calligraphy with sutras, or lines of scripture, and consultations with a Buddhist priest. (Photo by Yuya Shino/Reuters)

A member of Iraqi rapid response forces fires a rocket launcher during a battle with Islamic State militants in the district of Yarimja in southern Mosul, Iraq, January 18, 2017. (Photo by Alaa Al-Marjani/Reuters)

In this December 22, 2015, photo, Rayani Air flight crews prays before departure at Kuala Lumpur International Airport 2 in Sepang, Malaysia. Malaysia's Rayani Air took to the skies over the weekend with a clear bailiwick. It is the country's first Islamic airline, offering flights that adhere to Islamic rules including prayers, no-alcohol, no-pork meals, and a strict dress code for Muslim female flight attendants. (Photo by Joshua Paul/AP Photo)

An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

A “creuseur”, or digger, a plastic lantern on his head, readies to enter a copper and cobalt mine in Kawama, Democratic Republic of Congo on June 8, 2016. Cobalt is used in the batteries for electric cars and mobile phones. Working conditions are dangerous, often with no safety equipment or structural support for the tunnels. The diggers say they are paid on average US$2-3/day. (Photo by Michael Robinson Chavez/The Washington Post)

A handout photo made available by the NASA shows the United Launch Alliance Delta IV Heavy rocket launches NASA's Parker Solar Probe to touch the Sun, from Launch Complex 37 at Cape Canaveral Air Force Station, Florida, USA, 12 August 2018. Parker Solar Probe is humanity’s first-ever mission into a part of the Sun’s atmosphere called the corona. Here it will directly explore solar processes that are key to understanding and forecasting space weather events that can impact life on Earth. (Photo by Bill Ingalls/EPA-EFE/NASA)