The Walls of Benin were a combination of rampart

Defensive wall

A defensive wall is a fortification used to protect a city or settlement from potential aggressors. In ancient to modern times, they were used to enclose settlements...

s and moat

Moat

A moat is a deep, broad ditch, either dry or filled with water, that surrounds a castle, other building or town, historically to provide it with a preliminary line of defence. In some places moats evolved into more extensive water defences, including natural or artificial lakes, dams and sluices...

s, called Iya in the local language, used as a defense of the historical Benin City

Benin City

Benin City, is a city and the capital of Edo State in southern Nigeria. It is a city approximately twenty-five miles north of the Benin River. It is situated 200 miles by road east of Lagos...

, formerly of the now defunct Kingdom of Benin and now the capital of the present-day Edo State

Edo State

Edo State is an inland state in central southern Nigeria. Its capital is Benin City. It is bounded in the north and east by Kogi State, in the south by Delta State and in the west by Ondo State.-History:...

 of Nigeria

Nigeria

Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...

. It was considered the largest man-made structure lengthwise, second only to the Great Wall of China

Great Wall of China

The Great Wall of China is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups...

, and was hailed as the largest earthwork in the world. With more recent work by Patrick Darling, it has been established as the largest man-made structure in the world, larger than Sungbo's Eredo

Sungbo's Eredo

Sungbo's Eredo is a rampart or system of walls and ditches that is located to the south-west of the Yoruba town of Ijebu-Ode in Ogun state, southwest Nigeria . It was built in honour of the Ijebu noblewoman Oloye Bilikisu Sungbo, and is reputed to be the largest single pre-colonial monument in...

. It enclosed 6,500 km² of community lands. Its length was over 16,000 km of earth boundaries. It was estimated that earliest construction began in 800 AD and continued into the mid 1400's.

Description

The walls are built of a ditch and dike structure; the ditch dug to form an inner moat with the excavated earth used to form the exterior rampart.

The Benin Walls were ravaged by the British in 1897 during what has come to be called the Punitive expedition

Punitive expedition

A punitive expedition is a military journey undertaken to punish a state or any group of persons outside the borders of the punishing state. It is usually undertaken in response to perceived disobedient or morally wrong behavior, but may be also be a covered revenge...

. Scattered pieces of the structure remain in Edo, with the vast majority of them being used by the locals for building purposes. Sadly, what remains of the wall itself continues to be torn down for real estate developments.

The Walls of Benin City was the world's largest man-made structure. Fred Pearce wrote in New Scientist:

"They extend for some 16,000 kilometres in all, in a mosaic of more than 500 interconnected settlement boundaries. They cover 6,500 square kilometres and were all dug by the Edo

Edo

, also romanized as Yedo or Yeddo, is the former name of the Japanese capital Tokyo, and was the seat of power for the Tokugawa shogunate which ruled Japan from 1603 to 1868...

 people. In all, they are four times longer than the Great Wall of China

Great Wall of China

The Great Wall of China is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups...

, and consumed a hundred times more material than the Great Pyramid of Cheops. They took an estimated 150 million hours of digging to construct, and are perhaps the largest single archaeological phenomenon on the planet.