Three jiaoquan houses in Shanghai

This article on jiaoquan houses 绞圈房子 mentions that three such houses still survive in downtown Shanghai. The article focuses on a house in Zhoupu (two houses, actually). A little search revealed two more of these structures:

1) A courtyard house at Lane 780 Haining Road: 海宁路780弄22-24号 (I've not been there):

2) A residence in the old town, at 80 Aijia Lane 艾家弄80号.

Before I knew anything about jiaoquan houses 绞圈房子 I remember my fascination with the way its three interior courtyards are interlinked by a passage. I would not say this is the only instance of such architecture in the old town, but definitely one of the better preserved and least cluttered.

The history of the building on Aijia Lane is included in my book that is due by the end of the year. For now, here are some photos of the courtyard: