The Kyoto machiya, a house one room wide and forty meters deep

In old Kyoto, property tax was assessed on the width of a building where it met the street. Merchants responded the way merchants always do. They built narrow.

The result is the machiya, the wooden townhouse that shaped the city for four centuries. A typical one presents perhaps five or six meters of latticed facade to the road and then runs twenty, thirty, sometimes forty meters back. Kyoto people call them unagi no nedoko, eel beds.

The plan is a masterclass in solving a hard problem. Since light cannot come from the sides, it comes from above, through small internal courtyard gardens called tsuboniwa placed at intervals down the length of the house. These gardens do three things at once. They light the interior, they pull air through the whole building by convection in Kyoto's brutal humid summer, and they give every part of the house a view of something growing.

A dirt floored passage called the toriniwa runs the full depth along one side, so a delivery could go from the street to the storehouse without anyone stepping onto a tatami mat. The front room was the shop. The back rooms were family. Sliding paper and wood partitions meant the entire configuration could change for a funeral, a wedding or a hot afternoon.

Kyoto lost tens of thousands of machiya in the postwar decades to fire code, land value and the simple cost of maintaining timber. Surveys in the 2010s found that machiya were being demolished at a rate of roughly two a day.

The countertrend is real though. Craftsmen who know how to rebuild the joinery are booked years out. Old eel beds are becoming guesthouses, coffee shops and offices, keeping the courtyards.

Sit in one at dusk with the courtyard door open and you can feel the air move down the length of the house. Nothing is switched on. It just works.