For thousands of years, humans have been defending their cities by building huge walls around them. Over time, the cities often spill over the walls — but sometimes they remain hemmed in. Here are some incredible images that show what happens to walled cities over time.
A temporary fortification was built here during the Hannibal War (1644-1645) between Sweden and Denmark-Norway, but it became permanent in the 1660s. Over the next sixty years, some other fortifications were built and the old city center lost its dominance.
(via Google Maps and Walled Towns)
The Tuscanian city of Lucca has intact Renaissance-era city walls.
(via Google Maps and Replicant Dreams)
The fortified town of Carcassone was founded by the Visigoths in the fifth century on the remnants of a Roman fortress. It was enlarged in the 11th and 13th centuries, but later it was struck from the roster of official fortifications under Napoleon and the Restoration. It was almost demolished in 1849. Four years later, in 1853, Eugéne Viollet-le-Duc started to renovate the place — the complete restoration took almost six decades.
Nördlingen is about 3.7 miles (6 km) southwest of the centre of the Nördlinger Ries, which is a meteor impact crater formed about 14 million years ago. The stone buildings in Nördlingen contain millions of tiny diamonds – the crater created an estimated 72,000 tonnes of them from a local graphite deposit.
York has been defended by walls since the Roman times.
Taroudant, the "Grandmother of Marrakech", Morocco
In the sixteenth century the Saadi Dynasty used this city as a capital before Marrakech, and built a city wall and a mosque in 1528.
Toledo was the capital of the Roman province of Carthaginensis, the Visigothic Spain, and Spain before the Moors conquered it in the 8th century. The old city is surrounded on three sides by the Tagus River and there is a wall on the fourth.
(via Flickr/Nick McPhee)
The best preserved wall city in the world, Pingyao has 72 watchtowers and six giant gates.
This city with a double line of medieval walls from the 13th and 14th century is famous as a location in Dante's Inferno.
Most of the city's mud brick tower houses were built in the 16th century, and some of them are over 100 feet (30 meters) high.
Kowloon Walled City, Kowloon, Hong Kong
This largely ungoverned settlement was originally a Chinese military fort, but became an enclave after some areas were leased to Britain in 1898 for 99 years. After Japan's surrender in WWII, China wanted to reclaim its rights to the Walled City and 2000 people occupied the city in 1947. From the 1950s to the 1970s, it was controlled by Triads and had high rates of drug use, prostitution and gambling. It turned into the most crowded city ever. In 1987 the Kowloon Walled City contained 33,000 residents in its 6.5-acre (0.026 sq km, or 0.0102 sq mi) area. This German documentary has ten minutes of amazing footage from inside this metropolis.