The left branch was a different kind of space from the main channel.
The main channel felt like infrastructure. Not good infrastructure, exactly, but the kind that started with a plan. Then someone maintained it according to a different plan for long enough that both plans had slowly negotiated a compromise.
It still read as a sewer. The dimensions were correct. The water moved the way sewer water was supposed to move. The stone joins had the deliberate look of work done by people who had intended to build a sewer and mostly succeeded.
The left branch did not have that feeling.
The left branch felt like a space that had decided to become a passage because passages were the thing the surrounding space wanted. It had been doing that long enough that the result was convincing. Not correct, exactly. Just convincing.
The walls were close. Not dangerously close. Just the sort of close you get in places nobody with a measuring rod and opinions about width had ever visited.
