First built in the 1500s, Osaka Castle has been destroyed, rebuilt and repaired over the years. In the early 1900s one of the wooden columns supporting the castle's main gate, known as the Otemon Gate, rotted out at the bottom. Craftsmen patched this in 1923 with this peculiar splice:

I know the photo quality is poor. Here's a better photo of an identical splice joint executed by craftsman Chris Hall:

Image and work: Chris Hall

Following World War II, this splicing technique had been lost. Japanese craftsmen in the latter part of the 20th century had no idea how this splice was installed.

In 1983, the joint was X-rayed. The joint was reverse-engineered, and Japanese craftsmen (and eventually Western craftsmen like Chris Hall*) learned to make it again.

Here's how the mysterious joint goes together. I've cued this up to the right spot:

Enter a caption (optional)

The joint is referred to both by its technical name, basara-tsugi, and colloquially as the "Otemon splice."

It's one thing to see how it goes together; it's another to make the joint on-site. Imagine trying to chisel that thing out, upside-down, on the rotted column while it's in place. I imagine installation on-site is similarly fiendish; if you cannot jack the entire structure up, you'd need to remove foundation stones (in Japanese timber framing, the posts often rest on stacked stone pilings dug into the ground) to have the space to wedge the replacement part in.

----

*Chris Hall was a highly skilled craftsman who shared his knowledge on his website, The Carpentry Way, until his passing in 2020. Hall's widow maintains the website in Chris' memory. If you're interested in woodworking, I highly recommend checking it out.

The theme of the German Pavilion at Expo 2025 Osaka is the circular economy. The Berlin-based studio of architecture network LAVA designed the structures which are, unsurprisingly, circular:

Circular shape aside, visitors are meant to wend their way through the displays—which cover exhibitions of biospheres, circular cities with closed material and energy cycles, and examples of humans coexisting harmoniously with nature—in a linear fashion. Not literally, but meaning that there is a beginning and end to the exhibit hall.

What most caught my eye is the final room in this sequence, this "Circular Me" hall:

Within this space, designed by Cologne-based creative agency Facts and Fiction, "visitors reflect on personal choices, habits, and values. Through poetic imagery, thought-provoking questions, and a space that invites to pause, you're asked: 'What are you willing to change? What kind of future do you want to co-create?'"

The space is an interesting twist on the sunken living room/conversation pit, creating intimacy through a depression in the ceiling rather than the floor. And while I'm getting away from the theme of the exhibition here, the following occurred to me: If the screen was divided into four quadrants all showing the same thing, and if a lenticular effect could be created such that someone sitting at 6 o'clock could only see the screen centered on 12 o'clock, it would make for a rather novel home cinema.