《徐霞客游记·粤西游日记三》
转向北行一里，就见两旁山峰耸峙成峡谷，在中间修筑了城墙作为关口，以供过往出入，这是北门。
转北行一里，则两山耸峡，其中雉堞为关，而通启闭焉，是为北门。
I turned north and walked for a mile. I saw peaks towering on both sides, forming a canyon. A city wall was built in the middle as a pass for people to pass through. This was the north gate.