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Europe

In ancient Greece, large stone walls had been built in Mycenaean Greece, such as the ancient site of Mycenae (famous for the huge stone blocks of its ' cyclopean ' walls). In classical era Greece, the city of Athens built a long set of parallel stone walls called the Long Walls that reached their guarded seaport at Piraeus. Exceptions were few, but neither ancient Sparta nor ancient Rome had walls for a long time, choosing to rely on their militaries for defense instead. Initially, these fortifications were simple constructions of wood and earth, which were later replaced by mixed constructions of stones piled on top of each other without mortar.

The Romans later fortified their cities with massive, mortar-bound stone walls. Among these are the largely extant Aurelian Walls of Rome and the Theodosian Walls of Constantinople, together with partial remains elsewhere. These are mostly city gates, like the Porta Nigra in Trier or Newport Arch in Lincoln.

In Central Europe, the Celts built large fortified settlements which the Romans called oppida, whose walls seem partially influenced by those built in the Mediterranean. The fortifications were continuously expanded and improved.

Apart from these, the early Middle Ages also saw the creation of some towns built around castles. These cities were only rarely protected by simple stone walls and more usually by a combination of both walls and ditches. From the 12th century AD hundreds of settlements of all sizes were founded all across Europe, which very often obtained the right of fortification soon afterwards. Several medieval town walls have survived into the modern age, such as the walled towns of Austria, walls of Tallinn, or the town walls of York and Canterbury in England, as well as Nordlingen, Dinkelsbühl and Rothenburg ob der Tauber in Germany. In Spain, Avila and Tossa del Mar hosts surviving medieval walls while Lugo has an intact Roman wall.

The founding of urban centers was an important means of territorial expansion and many cities, especially in central and eastern Europe, were founded for this purpose during the period of Eastern settlement. These cities are easy to recognise due to their regular layout and large market spaces. The fortifications of these settlements were continuously improved to reflect the current level of military development.