The Great Wall is much more than a simple wall. Especially in its more developed areas, it is a complete defense system. Part of the enjoyment of walking the Great Wall is observing and admiring the ingenuity represented by its many interesting features. Let’s list some of the most important features that you should look for when you are at the Great Wall.

Watch towers

Watch towers are the main features that make the Great Wall much more than just a wall. Watch towers are enclosed structures that had multiple purposes. Primarily, they provided shelter to people defending the Great Wall.

Watch towers can have very elaborate designs, with multiple stories, with many rooms on each floor. Their design includes aesthetic as well as functional considerations. Aesthetic features include brickwork and carvings. Functional features include viewing and shooting holes, doors, windows, stairs, and fireplaces.

Watch tower at Jinshanling, Miyun, Beijing


In addition to watch towers, platforms can sometimes be found along the Great Wall. These are much less common than watch towers. They are often called fighting platforms, battle platforms, fighting terraces, or battle terraces.

Fighting platforms at Jinshanling, Miyun, Beijing

Platform at Huanghuacheng

Battlements or crenellation

The Great Wall is well known for its crenellations, or battlements. These are the up-and-down patterns made into the upper walls above the walking surfaces as well as the tops of watch towers for the purpose of protecting those defending the wall.

In order to conserve materials and labor, battlements were initially placed along only the “enemy” side (generally the north side) of the Great Wall to defend against the enemy. However, experience showed that it could become necessary to defend against the enemy on the south side of the wall as well, either during an attack where some of the enemy may have made it around to the south side of the Great Wall, or when attackers were returning from a successful raid.

Crenellations on the Great Wall at Mutianyu, Huairou, Beijing


Where battlements were provided only on one side of the Great Wall, parapets were often constructed on the opposite side. These are low walls that provide minimal enemy protection and keep the soldiers on top of the wall from having to worry about falling off the inside.

Barrier walls

Barrier walls are unfortunately named features that are often said to be designed to allow defending against an enemy that may have gained access to the top of the wall. In actuality, they are intended to provide a secure point from which to defend against an enemy on the ground near the wall where a steep incline makes normal battlements ineffective.

Barrier Walls at Jinshanling, Miyun, Beijing

Barrier Walls at Gubeikou military area, Miyun, Beijing
View from attacker's position

Barrier walls at Dongjiakou, Qinhuangdao, Hebei


Loopholes allowed viewing and shooting at the enemy while providing protection for the soldier. These holes were often constructed using purpose-built bricks with ornate decorations which differ from place to place. Other loopholes had decorations added after they were constructed.

Loopholes at Qinglongqiao, Yanqing, Beijing

Stone holes

Stone holes enabled dropping of rocks on any enemy who was close to the wall, while providing protection for the soldier. The system consisted of the hole (雷石口, léi shí kǒu), the beveled groove beneath the hole (雷石槽, léi shí cáo), and the stone itself (雷石, léi shí). The stone was a round, oblong, or rectangular rock which was sometimes hollowed out and filled with gunpowder. The gunpowder-filled stones exploded with great noise and shrapnel similar to a grenade, and so were known as “thunder stones”.

Stone holes at Gubeikou, Miyun, Beijing

Hindrance features

Many hindrance features were included to make it difficult for enemies to travel along the Great Wall if they were to gain access to the top.

High doorways were often included in towers so that it was very difficult to gain access to the tower without a ladder. The ladders could easily be pulled into the tower in case of attack.

High doorway on a tower, Simatai, Miyun, Beijing

Towers also included strong doors that could be bolted shut to prevent entry from the Great Wall on either side, or from the outside.

Narrow passageways were designed into the Great Wall to make it necessary for those moving along the wall to pass by one at a time.

Sometimes an incline features large steps which are too high to walk up or down. These steps had normal stairways that could easily be climbed, but they were located on alternating sides of the large steps, making it very slow and difficult to make one’s way up or down the incline.

Alternating steps at Manzhicao, Liaoning


On the enemy side of the Great Wall, ditches were often dug in order to provide an additional barrier to attackers and their horses. The material removed while digging these ditches was used in the construction of the wall.

Horse walls

In addition to ditches, some places have additional barriers known as horse walls that made it more difficult for enemies on horseback to attack the Great Wall. These are usually stone barriers of one to two meters in height.

Wall around important tower at Jinshanling

Brick course transitions

Bricks on inclined parapets normally run either horizontally or parallel to the incline. From time to time, it was necessary for builders of the Great Wall to transition from one style to the other. The way these transitions were designed varies from place to place. Here are a few examples.







Shentangling (Shentangyu)

Drainage features

The Great Wall builders of the Ming Dynasty knew that water can cause significant damage over time. They added many devices to the Great Wall in an effort to remove and control rain water.

The Ming Dynasty Great Wall contained extensive drainage features to manage rain water in order to prevent damage to the wall. Vast quantities of rain water can run down long inclines and cause erosion in a surprisingly short time. To prevent this, channels were incorporated in the surface of the wall to divert water to spouts and drain systems.

Water barriers running transversely across the surface of the Great Wall
discharge water and prevent it from running down (Huanghuacheng)
These are often found at low spots or along extended inclines

Water spouts at the top of Kylin Tower (Jinshanling)

A water barrier that diverts water to a shooting hole in the side of the Wall (Jinshanling)

Water spouts at the top of a tower (Mutianyu)

Water channels run water along the Wall on the enemy side where water spouts might aid climbing (Mutianyu)

Water spouts can enable climbing; I have used them myself. (Qinglongqiao)

A loose spout (Hefangkou)

Transverse water channel routed to a drain hole (Mutianyu)

A narrow water spout (Mutianyu)

A loose spout (Mutianyu)

A water spout (Mutianyu)

A water spout with a splash tray below (west of Badaling)

A splash tray beneath a water spout (Qinglongqiao)

Transverse channel and drain hole (Qinglongqiao)

Transverse channel and drain hole (Qinglongqiao)

Transverse channel and drain hole (Badaling)

Transverse channel and water spout (Qinglongqiao)

Water spout (Qinglongqiao)

Transverse channel and drain hole above a longitudinal drain channel on north (enemy) side (Qinglongqiao)

Detail of longitudinal drain channel on north (enemy) side (Qinglongqiao)

Water spout (Qinglongxia)

Water spout (Shangguan)

Water spout (Shixiaguan)

Water spout (Shixiaguan)

Water spout atop a tower (Shixiaguan)

Water spout (Shixiaguan)

Water spout (Shixiaguan)

Water spout atop a tower (Xishuiyu)

Crowns atop parapets divert water (Xiangshuihu)

Drainage feature at Badaling, Yanqing, Beijing

Drainage feature at Badaling, Yanqing, Beijing

Cut stone foundations

In looking at the Great Wall from the outside, one would assume that, like bricks, the cut stone foundation blocks are rectangular cuboid in shape, that is, all of the angles are approximately 90-degree or right angles. It’s only when you get the opportunity to see the insides of these stones that you learn that this isn’t so. Often the inner parts of these stones are cut in such a way as to reduce weight and material usage. The inner faces of the ends often taper inward at angles of greater than 90 degrees.




Signal towers

In addition to the towers that are a part of the Great Wall, freestanding towers were sometimes built in strategic points that provided good views of the surrounding areas as well as high visibility from afar. These towers were used for viewing the enemy and for sending signals along the wall regarding enemy attacks. Signaling was typically done using smoke in the daytime and fire at night.

Round signal tower at Jinshanling, Miyun, Beijing

Smoke stacks

In addition to signal towers, smoke stacks were sometimes constructed in key areas. A row of several smoke stacks enabled sending a signal consisting of varying numbers of smoke streams, signifying the relative size of an attack.

Smoke stack ovens

Horizontal lines

I noticed these prominent horizontal lines at the eastern side of the Lianhuachi Great Wall. I can only assume that the wall was originally built to the height of the line and then later the height of the wall was increased to its present height, leaving the line showing the obvious, earlier position of the top of the wall.