Bhir

The oldest part of Taxila is Bhir (satellite photo), which consists of several building phases:
the oldest stratum, usually dated to the sixth and fifth centuries BCE, although literary sources suggest that the city is a bit older;
the fourth century, in which raja Ambhi entertained Alexander the Great in 326;
the stratum of the Mauryan empire, third century (the picture shows a part of the recently excavated water system);
and the uppermost stratum, which is everything after the Mauryan period.