Obscura Day featured events such as a caravan of cars assembled near Los Angeles, which drove into the Mojave Desert to a city that was abandoned before it ever got started.
In the 1950s the road grid was laid out for California City, but it never went any further.
“It was going to rival Los Angeles in size and they laid out all the street grids and never built the town, so it’s this kind of haunting abandoned city,” says Joshua Foer, the co-founder of the Atlas Obscura website, which organised the day.
Although Foer is careful not to have a favourite event.
“They’re like my children," he says. "I love them all equally."
In Belgium, there was a trip to the Eben Ezer tower, a seven-storey castle built designed by Robert Garcet, and constructed by hand in the 1960s from flint stone rubble.
“It is deeply, thrillingly, exuberantly odd,” said Ed Cooke, the organiser of the tour. “It is quite the silliest thing.”
In Paris, there was a special tour of the Musée Fragonard, where you can find the skulls, livers and stomachs of any animal you care to name, as well as a cabinet of monsters.
The museum takes its name from an 18th century collection of anatomical models made from flayed figures created by Honoré Fragonard. The models, which are known as écorchés, are dissected animals and humans, created by a secret process in the 18th century.