Nanjing Ming City Wall 南京明城墙

Welcome, everyone! You've arrived at the Nanjing Ming City Wall. Today I'll be guiding you along a route that takes in all the highlights: Zhonghua Gate Plaza, the first gateway, the barbicans and hidden soldier caves, the ramps, the top of the wall, the Nanjing City Wall Museum, and the Taicheng section. Together we'll explore a fortification that has stood for six hundred and fifty years — the greatest ancient city wall in the world.

Let's start with the basics of the Nanjing Ming City Wall. This is no ordinary wall. It is the longest ancient city wall ever built — originally 35.267 kilometers at the time of its Ming-dynasty construction, with 25.091 kilometers still standing today, making it even longer than the Ming city wall in Beijing. The Hongwu Emperor Zhu Yuanzhang took the advice of his strategist Zhu Sheng to "build high walls, stockpile grain, and be slow to claim the throne." Starting in 1366, he mobilized 280,000 laborers and spent 28 years consuming 350 million bricks to create this unmatched feat of military engineering.

What makes the Nanjing City Wall so unusual? Nearly every ancient Chinese capital wall — Xi'an, Pingyao, you name it — is a neat rectangle. Nanjing's is completely different. It follows the natural contours of the landscape, weaving the Qinhuai River, Xuanwu Lake, and Purple Mountain into its defensive system. This was the genius of Zhu Yuanzhang's military strategist Liu Bowen: use the natural terrain as your shield — far more effective than any man-made moat. The wall also consists of four concentric rings — Palace City, Imperial City, Capital City, and Outer City — layered like rings around a core. There is nothing quite like it anywhere else in the history of urban construction.

The magnificent gate in front of us is Zhonghua Gate. Once known as Jubao Gate ("Gate of Accumulated Treasure"), it is the largest and most structurally complex ancient city gate in China, celebrated as the "Number One Barbican Under Heaven." Look up at the plaque above the gateway — those three characters reading "Zhonghua Gate" were inscribed by Chiang Kai-shek in 1931, when the Nationalist government gave the gate its current name. The shift from "Jubao" to "Zhonghua" is itself a piece of history compressed into a name.

Now let's cross Zhonghua Gate Plaza and step up to the base of the first gateway. Take a moment to look up and feel the height — 21.45 meters, roughly equivalent to a seven-story building. In the age of cold weapons, six hundred years ago, that height alone was enough to stop any attacking force in its tracks.

Move closer and look up at the ceiling of the gate tunnel. See those two vertical grooves running from top to bottom? About 20 centimeters wide and 18 centimeters deep — those are the portcullis slots. During the Ming dynasty, every one of the four gateways was fitted with double iron-clad wooden doors and a portcullis: a heavy wooden panel sheathed in iron, raised and lowered by a windlass mechanism set into the masonry above. Picture the scene: enemy soldiers smash through the first wooden door and charge in — then the portcullis crashes down from above, cutting off their retreat. And on the stone walls flanking the tunnel, you can still see the bolt-slot marks — once the gate was shut, soldiers would drive massive wooden crossbars through from the inside, making it nearly impossible to batter open from without.

Now look down at the bricks beneath your feet. On the side face of nearly every brick, you'll find text: the name of the kiln district, the supervising official, and often even the individual brick-maker and laborer. Inscriptions like "Supervising Official of Ji'an Prefecture, Jiangxi Province, So-and-So" or "Kiln master Zhang San" and "Laborer Li Si." Why did Zhu Yuanzhang require every single brick to be named? This was the world's earliest large-scale quality-traceability system — if a brick failed, the name on it led straight back to the person responsible. So craftsmen fired their bricks with extraordinary care. Every brick had to meet the standard of "ringing when struck, showing no voids when broken." Six hundred and fifty years of wind and rain later, these bricks remain as solid as ever — and those ordinary workers' names have, quite unexpectedly, become permanent.

We've passed through the first arched gateway and entered the first barbican. Look ahead — there are three more gateways to go. Zhonghua Gate's defensive system consists of three successive barbicans and four gateways. Seen from above, the entire layout resembles the Chinese character for "eye." What is the core idea behind this design? It is the ancient stratagem of "catching turtles in a jar."

Let me reconstruct the battle scene from six hundred years ago. Suppose the enemy breaches the first gateway and a mass of soldiers floods into this barbican. Behind them, the portcullis drops — no retreat. Ahead, the second gateway stays firmly shut. Defenders in the hidden soldier caves on all sides of the barbican open fire simultaneously: arrows rain down, logs and boulders roll off the walls above. The attackers are trapped in an enclosed space 120 meters long and 118 meters wide, with nowhere to run. And if by some miracle the enemy forces their way past the second gate, they immediately face a third — and then a fourth. Each one is a fresh death trap. This is the most terrifying thing about Zhonghua Gate's military design: it does not try to keep the enemy out. It lets them in — and then tears them apart.

Now turn toward the inner face of the wall — see those arched openings? Those are the hidden soldier caves. Zhonghua Gate contains 27 of them in total: 7 in a row on the inner mid-level of the main gate, 3 on each side of the lower passageway, and 14 beneath the east and west ramps. Each cave is built with a brick-and-stone barrel vault, stands roughly 2.5 to 3 meters high, and has concealed ventilation shafts that also let in light.

How were these caves used in actual combat? At full capacity they could shelter over 3,000 soldiers and stockpile vast quantities of military supplies — grain, arrows, gunpowder, and stone shot. Imagine three thousand fully armed soldiers hidden inside the wall, then pouring out of every cave mouth the moment battle is joined, surrounding the enemy already trapped in the barbican from all directions. Concealing troops inside the fabric of a fortification itself was extremely rare among European castles of the same era. Stand here for a moment and feel it — every inch of ground you're standing on, six hundred and fifty years ago, may well have hidden a soldier ready to charge.

From a modern structural engineering perspective, these caves are remarkable in their own right: not a single timber beam, not a single iron nail — the entire load is transferred through the precise interlocking geometry of the brick vault. The fact that Zhonghua Gate has survived centuries of warfare and natural disaster owes a great deal to this barrel-vault masonry technique.

Stepping out of the hidden soldier cave area, notice the two broad sloping corridors on the east and west sides of the wall — those are the ramps. Each is 11.5 meters wide and 86.1 meters long, steeply graded, paved with large bricks, and fitted with transverse ridges to stop horses from sliding.

Pay attention to the grade of the ramp. This is not a staircase — it is a slope designed for horses to gallop up and down at full speed, which was a remarkably refined feature of ancient military engineering. In wartime, commanders could ride their horses straight up to the battlements to direct the battle; supply soldiers could carry heavy cannons, ammunition, rolling logs, and stone shot up to the top in pairs. In the heat of combat, the ramps were the wall's lifeline.

Now look at what's underneath the ramps. The interior space beneath both slopes was cleverly converted into 14 hidden soldier caves, making full use of the void inside the ramp structure. This kind of multi-purpose, space-efficient thinking was remarkably forward-looking for a civil engineering project from over six hundred years ago. The ramps are also a great spot for photography — standing halfway up and looking back at the full breadth of the barbican gives a powerful sense of depth, especially in the late afternoon when the sun comes in low from the west and brings out the texture of the brick in rich layers.

We've climbed the ramp and reached the top of the wall. Walk to the merlons and look south — the wide river flowing below is the Outer Qinhuai River, and the Changgan Bridge connects this bank to Yuhuatai on the other side. In the Ming dynasty, Yuhuatai was a military high ground just south of the city, and Zhonghua Gate was the first line of defense against any force advancing from that direction. Now look north — the Inner Qinhuai River flows from east to west; on its far bank is the lively Laomendong historic district, and in the distance the glazed tile tower of the Dabao'en Temple catches the sunlight with a golden gleam. Six hundred years ago, when Zhu Yuanzhang stood here, he looked out over the same Qinhuai waterscape, the same merchant boats moving along the same river.

Take a moment to look down at the bricks beneath your feet. The top of the wall ranges from 10 to 18 meters wide — broader than the walls of most European castles of the same era, wide enough for two war chariots side by side. Every single brick carries a name, and every name is a trace of an ordinary person's life.

A photography tip. Walk about fifty meters west along the top of the wall and look back toward the main gate of Zhonghua Gate. From there you can capture all three layers of the barbican's "eye" formation in a single frame, with a dramatic sense of depth and scale. The light in early morning and at dusk hits the brickwork at an angle, and that's when the inscriptions and textures show up most clearly.

Leaving the Zhonghua Gate complex and walking east for less than two minutes, you'll reach the Nanjing City Wall Museum. The building itself is a work of art — it sinks largely underground, its glass curtain wall modestly reflecting the six-hundred-and-fifty-year-old arrow tower of Zhonghua Gate, old and new in quiet conversation through light and shadow. The total floor area is 12,000 square meters. It opened in 2021 as China's first museum dedicated to ancient city walls and holds the status of National First-Class Museum.

Once inside, head straight for the centerpiece of the permanent exhibition "The Unparalleled City Wall" — the Brick Inscription Wall. An entire wall is lined with over 600 varieties of Ming-dynasty bricks, representing nearly 200 production units across the five provinces of Jiangsu, Jiangxi, Anhui, Hunan, and Hubei. Every brick carries text: the supervising official's title, the kiln master's name, the laborer's home district, and even the waterway used during transport. The museum's brick archive lets you scan a code with your phone and pull up the complete provenance of any brick on display — where the clay was dug, who fired it, who oversaw production, and which river route brought it to Nanjing. One brick carries the clear impression of a craftsman's fingerprint — pressed in accidentally during firing, then preserved across six hundred and fifty years. History suddenly feels warm to the touch.

The museum also reconstructs a Ming-era brick quality-inspection station and displays ancient siege and defense weapons along with the wooden pile foundations from the Ming Imperial Palace. Practical note: admission is free, but you must book in advance through the "Nanjing City Wall" WeChat public account at least three days ahead. Flash photography is strictly prohibited inside. If your schedule allows, make your way to the museum's rooftop terrace in the final hour before closing — it's the best vantage point for a sweeping overhead shot of Zhonghua Gate.

Three things to take away from the Nanjing Ming City Wall.

First: this is the largest ancient city wall in the world — built by Zhu Yuanzhang over 28 years, by 280,000 pairs of hands, using 350 million bricks. The name of a craftsman is stamped into every single one of those bricks. It is the earliest large-scale quality-traceability system ever put into practice, anywhere on earth.

Second: the three barbicans and 27 hidden soldier caves of Zhonghua Gate represent the pinnacle of ancient Chinese military engineering. "Catching turtles in a jar" is not just a figure of speech — it was a fully realized war machine built from real brick and mortar, capable of concealing three thousand soldiers inside a city gate.

Third: when you stand on the Taicheng wall, Purple Mountain's ancient green stretches away on one side, Xuanwu Lake's vast water shimmers on the other, the bell of Jiming Temple carries on the wind behind you, and the city's ten thousand lights glow ahead. Six hundred and fifty years is no more than the blink of an eye — and yet this wall still stands, still holding watch over every last inch of Nanjing.

Before you go, Nanjing has more to offer: the remarkable "Ghost Face Gazing in the Mirror" at Shitou Cheng, the well-preserved Qing-dynasty watchtower at Shence Gate, and several other climbable sections of the wall including Qingliang Gate and Dongshuiguan. Thank you for joining me today — I hope Nanjing leaves you with a journey worth remembering.