Which preposition to use with seleucia

on Occurrences 2%

VAN INGEN, WILHELMINA. Figurines from Seleucia on the Tigris.

by Occurrences 1%

Crassus was intending to advance to Seleucia by such a route as to reach there safely along the side of the Euphrates and on its stream, with his army and provisions.

Which preposition to use with  seleucia