<P> In the 6th century BC, Ionian Samos developed the double - colonnaded dipteros as an alternative to the single peripteros . This idea was later copied in Didyma, Ephesos and Athens . Between the 6th and the late 4th century BC, innumerable temples were built; nearly every polis, every colony contained one or several . There were also temples at extra-urban sites and at major sanctuaries like Olympia and Delphi . </P> <P> The observable change of form indicates the search for a harmonious form of all architectural elements: the development led from simpler early forms which often appear coarse and bulky up to the aesthetic perfection and refinement of the later structures; from simple experimentation to the strict mathematical complexity of ground plans and superstructures . </P> <P> From the early Hellenistic period onwards, the Greek peripteral temple lost much of its importance . With very few exceptions, Classical temple construction ceased both in Hellenistic Greece and in the Greek colonies of Magna Graecia . Only the west of Asia Minor maintained a low level of temple construction during the 3rd century BC . The construction of large projects, such as the temple of Apollo at Didyma near Miletus and the Artemision at Sardis did not make much progress . </P> <P> The 2nd century BC saw a revival of temple architecture, including peripteral temples . This is partially due to the influence of the architect Hermogenes of Priene, who redefined the principles of Ionic temple construction both practically and through theoretical work . At the same time, the rulers of the various Hellenistic kingdoms provided copious financial resources . Their self - aggrandisation, rivalry, desires to stabilise their spheres of influence, as well as the increasing conflict with Rome (partially played out in the field of culture), combined to release much energy into the revival of complex Greek temple architecture . During this phase, Greek temples became widespread in southern Asia Minor, Egypt and Northern Africa . </P>

What architectural feature is essential to the classical greek temple