ISTANBUL — Few archaeological sites seem as entwined with conflict, ancient and modern, as the city of Karkemish.

The scene of a battle mentioned in the Bible, it lies smack on the border between Turkey and Syria, where civil war rages today. Twenty-first century Turkish sentries occupy an acropolis dating back more than 5,000 years, and the ruins were recently demined. Visible from crumbling, earthen ramparts, a Syrian rebel flag flies in a town that regime forces fled just months ago.

A Turkish-Italian team is conducting the most extensive excavations there in nearly a century, building on the work of British Museum teams that included T.E. Lawrence, the adventurer known as Lawrence of Arabia. The plan is to open the site along the Euphrates river to tourists in late 2014....