Are there any partial doors in traditional houses in Beijing?

In some alleys and hutongs, there are some entrance doors called "side doors", which are usually set on the side, also known as "side doors". These doors usually do not face the street, and are composed of low walls and fences on the side walls. Some of them are in the corners of open spaces, which are inconvenient and have no obvious house numbers, so they are easy to miss.

The "side door" is usually only enough for one person to pass through. In the past, the "side door" was usually used as an exit for escapees.