长城词典·关口又称关、关隘、关塞，是长城的出入口，设置在交通通道上或要塞处的城墙上，供行人及车马通行。关口均设关门，平时查验过往行人及商旅，战时闭门御敌。临河而设的关口往往设有水门，防止敌人沿河道侵入。要道关口或水门上多建有关楼，或在关门内侧建有房屋，供守关士兵居住。重要关口在关内建有关城，为驻兵提供生活屯田保障及练兵场地。仅通步骑的山坳处小关口，建筑比较简单，仅修建涵洞式小关门。 Great Wall dictionary·Pass GatePass Gate，also known as the gateway of the pass，is the passageway of the Great Wall. It is built on the transportation route or the wall of the stronghold，providing passageway for pedestrians，carriages and horses. The Gate is usually set at the pass. Normally，belongings of passersby and cargoes of travelling merchants are checked here. During wartime，the gate is closed to keep the enemies out. Pass gate located on the bank of the river is usually set with water gate in order to prevent the enemies from invading through the river way. Pass towers are often built on important pass gates and water gates. In other cases，houses are built inside the pass gate to provide accommodation for the soldiers. Pass town is also built inside the important pass，which provides the soldiers with daily provisions and agricultural production as well as drilling fields. The building of small pass gate located at col is quite simple，in which small pass gate similar to the culvert is built.
