Fortifications (Roman military engineering)

• The longest city walls were those of Classical Athens. Their extraordinary length was due to the construction of the famous Long Walls which played a key role in the city's maritime strategy, by providing it with a secure access to the sea and offering the population of Attica a retreat zone in case of foreign invasions. At the eve of the Peloponnesian War (431–404 BC), Thucydides gave the length of the entire circuit as follows: 43 stades (7.6 km) for the city walls without the southwestern section covered by others walls and 60 stades (10.6 km) for the circumference of the Peiraeus port. A corridor between these two was established by the northern Long Wall (40 stades or 7.1 km) and the Phaleric Wall (35 stades or 6.2 km). Assuming a value of 177.6 m for one Attic stade, the overall length of the walls of Athens thus measured about 31.6 km. The structure, consisting of sun-dried bricks built on a foundation of limestone blocks, was dismantled after Athens’ defeat in 404 BC, but rebuilt a decade later. Syracuse, Rome (Aurelian Walls) and Constantinople (Walls of Constantinople) were also protected by very long circuit walls.