In various forms the Hellenistic architectural tradition flourished over a very wide area, and many Hellenistic buildings and complexes survived relatively intact through later antiquity. From the second quarter of the fourth century onward kings and local dynasts of the Eastern Mediterranean founded an unprecedented number of new cities with grid-plans of classical Hippodamian type. There were apparently several regional schools of Hellenistic townplanning. Hellenistic stoas were often two-storeyed, and effectively defined the borders of large open areas, for example the Athena precinct at Pergamum, or the Athenian Agora. Ptolemaic palaces in fact remained unrivalled until the time of Nero and the Flavians; yet both in Alexandria and at Vergina and Samos, Greek, or Graeco-Egyptian, columnar orders formed the basis of most of the designs. Probably no other period, either of Greek or of Roman architecture, can advance as impressive a claim to originality as the centuries from C 350 to 100.