I’m sure you all have read about the Kyushu earthquake by now. It was a pretty big one. One casualty of the quake was Kumamoto Castle. The roof and stone wall of the castle were damaged.
The Spoon & Tamago blog tells us this was by design:
The primary damages appears to be of the stone walls and tile roofing, which were dislodged and collapsed. The tile roofing, in particular, slide off the roof and fell to the ground, causing large plumes of smoke to rise and cause alarm. However, according to some, this was an entirely intentional mechanism of ancient Japanese architecture designed to protect structures from collapsing during earthquakes.