There’s not much to say about this, but it’s wonderfully picturesque: Standing near the village of Plougrescant on the coast of Brittany is Castel Meur, “the house between the rocks.”

Constructed in 1861, it’s situated between granite rocks to protect it from storms.

01/28/2020 UPDATES:

Casa do Penedo, in northern Portugal, has boulders for its foundation, walls, and ceiling. (Thanks, Rui.)

Wickhams department store planned an imposing new edifice in London’s East End in 1923, but the Spiegelhalter family refused to sell its jewelry shop, so the Wickhams facade had to be built “around” it. The “Spiegelhalter gap” was never closed — the department store closed in the 1960s, while the jewelers’ held out until 1982. (Thanks, Nick.)

St. Govan’s Chapel in Pembrokeshire, Wales, is built into the side of a limestone cliff — visitors must climb down a flight of 52 stairs to reach it. (Thanks, Chris.)

In 1993, Tennessee minister Horace Burgess was praying when God told him, “If you build a treehouse, I’ll see that you never run out of material.” He set to work and spent the next 12 years building a house 97 feet tall, unofficially the largest in the world.

The house was closed in 2012 because it didn’t follow building and fire safety codes, and last October it burned to the ground. Burgess told the New York Times that in some ways this was a relief. Though it had been important to him for decades, “It’s always been a pain,” he said.

Austin game developer Frank Force has won the Neural Correlate Society’s 2019 Best Illusion of the Year Contest with this “dual axis illusion”:

“This spinning shape appears to defy logic by rotating around both the horizontal and vertical axis at the same time! To make things even more confusing, the direction of rotation is also ambiguous. Some visual cues in the video will help viewers change their perception.”

The top 10 finalists are here.

12/18/2019 UPDATE: Good heavens, people are making these things. Five years ago Bill Gosper created the Lissajoke ambiguous roller, which rolls in a perplexing way:

And reader Joe Kisenwether has rendered Force’s illusion in reality — here the shape on the left spins about a horizontal axis while the one on the right spins about the vertical one:

The same thing rendered more slowly:

(Thanks, Joe.)

A drop of ink has fallen upon the paper and I have walled it round. Now every point of the area within the walls is either black or white; and no point is both black and white. That is plain. The black is, however, all in one spot or blot; it is within bounds. There is a line of demarcation between the black and the white. Now I ask about the points of this line, are they black or white? Why one more than the other? Are they (A) both black and white or (B) neither black nor white? Why A more than B, or B more than A? It is certainly true,

First, that every point of the area is either black or white,

Second, that no point is both black and white,

Third, that the points of the boundary are no more white than black, and no more black than white.

The logical conclusion from these three propositions is that the points of the boundary do not exist.

— Charles Sanders Peirce, “The Logic of Quantity,” 1893