Circumstances that explain the urban development refer to the defensive reasons that justify the different fortified layouts during the centuries Crete, with its many advantages, its key geographic position and its fertile soil, was a prize sought by a succession of invaders and attackers over the centuries. The turbulent history of the island affected the development of its cities and of the way they were protected and defended against hostile threats. Within the administrative organisation of the Byzantine Empire, Crete was a separate province, with a largely pastoral and agricultural economy. During this period Crete suffered repeated natural disasters and enemy attacks. In 623 it was attacked by Slavs, while the Turkish menace was already beginning to loom by the middle of the 7th century. The Arab fleet made frequent raids on the island before finally seizing it in 823. It was in the turbulent period of the 6th or 7th century that the Byzantine defensive wall was raised around Chania, on the trace of the earlier Hellenistic fortification wall. In those critical times Crete, as a Byzantine province, did not have strong defences. The internal crisis afflicting Byzantium in this period led it to neglect its coasts and islands, and this gap in its defences was exploited by the Saracens. The loss of Crete was a severe blow to Byzantium. With Crete, it lost not only a large province but also control of trade and the sea routes in the sensitive region of the Eastern Mediterranean. The retaking of Crete was not merely a question of prestige, but a matter of vital importance for the safety of the seas. Crete was liberated by Byzantine general Nicephorus Phocas in 961. The first matter of business for the Byzantine Empire immediately after their recovery of the island was to restore and consolidate their rule, so that the defences of the island could be organised as rapidly as possible to meet, promptly and effectively, any attempt on the part of the Arabs to retake it. The vigilance of the navy was organised immediately, and strong fortifications were raised around the coasts. It was in this framework that the existing Byzantine walls of Chania were repaired and reinforced. Venice began showing an interest in Crete early in the 12th century, in the context of the Serene Republic’s designs upon the trade routes of the Eastern Mediterranean. In 1204 Venice bought the island from Bonifacius Montiferrati Marchio, to whom it had been awarded as a prize by the leaders of the Fourth Crusade. The Venetians settled in Crete in 1211, and immediately began to organise the administration of their new acquisition. The city of Chania was an important political and commercial centre, capital of the region (sestiere) of Dorsoduro and second in importance to the capital of Candia (Heraklion). The Venetian colonial installations in Chania and other Cretan cities had to face continual uprisings and insurrections through the 13th and 14th centuries. Protection against the intense hostility of the local population forced the Venetians to settle in the existing fort on Castelli Hill; they reinforced its fortifications, and built their new establishments behind its walls. To assure the safety of their maritime communications, this time against external attack, the Venetians built defensive works on the Bay of Chania; these included the fortification of the islet of Agii Theodori (or Thodorou) with two forts and of the Bay of Souda with a system of fortresses, of which the most important is that on the islet of Agios Nikolaos. Chania is the centre of a fertile district, and the surrounding large settlements on the plain and the promontory (Akrotirion) contained several wealthy manor houses belonging to feudal overlords. Manufacturing activity developed in the town, and the port was the hub of maritime communications in the Eastern Mediterranean. The needs of the city gradually increased through the 14th century, as relations between the Venetians and the local population improved; and the scattered villages of labourers that had clustered around the fortified hill rapidly developed into suburbs, or b?rghi. By this time it was obvious that tiny Castelli was insufficient to defend the population against the increasingly numerous pirates that plagued the Aegean, and the Venetian administration was therefore obliged to erect a second and more extensive defensive wall, which was begun in about 1540. It was not long, however, before this too proved insufficient. Turkish forces had been threatening the Venetians with increasing severity since the early decades of the 16th century, and the series of four wars between the two powers over the course of that century culminated in the bloody struggle in which the Venetians lost Cyprus (1570-1573). At the same time, rapid progress in military architecture and the art of war made it essential to assure effective defences for the city and its suburbs and for the protection of the port. The Venetians decided to fortify the cities and other key points in this invaluable colony; and from 1538 to the eve of the Turkish seizure of the city they worked on the construction of a new enclosure wall in accordance with contemporary bastionate fortification principles, while at the same time paying particular attention to the defences of the harbour. The siege and capture of the city by the Turks in 1645 ushered in a new period in the city’s history that would last until the end of the 19th century. The city was as important to the Ottoman Empire as it had been to the Venetians, but its new rulers paid little attention to maintaining either its fortifications or its port installations, beyond repairing breaches after raids and adding a few new elements, like cavalier towers and small forts. As the city remained confined within the limits of its fortifications, the housing problem created by the concentration of population within the walls was resolved by erecting multi-storey wooden buildings. The increasing pressures exerted by a growing population and the city’s new requirements for functional space in the latter part of the 19th century led the Turkish administration to permit the installation of some undesirable land uses outside the defensive ditch beyond the walls – including, for example, graveyards and the leper colony; while outside the eastern walls a whole Bedouin village came into being. The rising and increasingly prosperous middle classes also began to look beyond the densely crowded urban core. Wealthy landowners and merchants, foreign consuls and prominent Turks and Egyptians built their houses outside the walls, mainly on the eastern side of the city, in the Halepa district, which rapidly developed into a wealthy suburb. A certain amount of effort was also devoted at this time to creating rural roads (starting with the road to Halepa); and it was outside the walls that the first European-style public park was built, in 1870. By this time it was obvious that the fortifications were more of an obstacle to the growth of the city than a mechanism for its defence. This realisation, combined with the relative security afforded by the creation in 1898 of a semi-independent Crete with its capital at Chania, and even more with the island’s union with Greece in 1913, led to the functional depreciation of the fortifications. A modernisation and development plan drawn up for the city in 1901 called for significant expansion. It was then that the demolition of the walls began, for the purpose of assuring easy communications between the inner and the outer city. Sections of the eastern, southern and western walls were pulled down, new openings were made, and the perimeter ditch was rapidly filled in. A new municipal market was built on the site of the Piatta Forma, new roads were laid out and, later, new public buildings were built in many other places. Meanwhile, measures for the protection of the Byzantine and Venetian walls would have to wait until the 1960s.