n.城或墙顶之垛口；枪眼；炮门

The Mutian Valley Great Wall's construction has the unique style, here watch tower is crowded, the mountain pass is important, the city both sides have the crenel. 慕田峪长城的构筑有着独特的风格，这里敌楼密集，关隘险要，城两侧均有垛口。

The city is square, the fence is 12 meters or so high, build by laying bricks or stones of outside and total brick, build on the wall have crenel, there is moat outside the wall. 城为方形,墙高12米左右,外表全部砖砌,墙上筑有垛口,墙外有护城河。

Low is called the bench table, highly with city wall difference not many, but outside the prominent wall, all around has the crenel, is place which the patrol stands sentry. 低的叫墙台，高度与城墙 相差不多但突出墙外，四周有垛口，是巡逻放哨的地方。