In 2009, in the little Swiss town of Teufen, conceptual artists Frank and Patrik Riklin converted a 1980s-era nuclear fallout shelter to the “Null Stern Hotel,” an underground facility that accommodates 14 guests in a concrete bunker fitted with blast doors nearly two feet thick.

“We kept the internal structure of the shelter intact — the concrete and the ductwork — and then we added the warmth of antique beds and furniture,” Patrik told the Guardian. “For us it’s an art installation before it’s a hotel — a place where people can think about their surroundings.” There are no windows, only a CCTV camera displaying the outside world, and they retained the institutional paint scheme of pastel blue and yellow.

The site was nominated for best innovation of the year in the 2009 Worldwide Hospitality Awards, and GEO magazine ranked it among the Top 100 hotels in Europe the following year. In 2010 the proprietors were seeking to expand the franchise, but to date no hotel has opened beyond Teufen.

I send you a photo of myself for ‘Curiosities’ studying Virgil in a peculiar position. It was taken by my brother in the country a few weeks ago. It was not a snap-shot, but a time exposure.

— Charles E. Williams of Rock Ferry, Cheshire, in Strand, September 1905

Australia’s Mount Wingen has been burning for 6,000 years. A lightning strike or brush fire ignited a coal seam there around 4000 B.C., and it’s been smoldering ever since.

“Smoldering fires, the slow, low-temperature, flameless form of combustion, are an important phenomena in the Earth system, and the most persistent type of combustion,” University of Edinburgh fire scientist Guillermo Rein told the New York Times. “The most important fuels involved in smoldering fires are coal and peat. Once ignited, these fires are particularly difficult to extinguish despite extensive rains, weather changes or firefighting attempts, and can persist for long periods of time (months, years), spreading deep (5 meters) and over extensive areas of forest subsurface. Indeed, smoldering fires are the longest continuously burning fires on Earth.”

The Mount Wingen fire holds the Guinness record for the longest-burning fire in the world.

Hui Tzu argued that a motherless colt never had a mother.

For when it had a mother, he said, it was not motherless.

And at every other moment of its life, it had no mother.

The United States minted nearly half a million copies of this 20-dollar gold coin in 1933, but when gold coins were disallowed as legal tender most of them were melted down. The mint saved two for the U.S. National Numismatic Collection, and 20 more were stolen. Of these, nine have now been destroyed, and 10 are held at Fort Knox. That means that a total of 13 specimens of the 1933 double eagle are known to exist, with only one in private hands. Shoe designer Stuart Weitzman, who had paid $7.6 million for that one in 2002, auctioned it last month to an anonymous collector for $18.9 million. That coin is unique: No other 1933 double eagle can be privately owned or legally sold.