the Pont du Gard
is a Roman aqueduct built during the first century AD. It is part of
a system which carried water from Uzès to Nimes (Roman colony
of Nemasusus) France. It’s built on three levels, it’s 274 m long, and
the limestone blocks are precisely cut, eliminating the need for mortar.
Some have a “keyed” or “tongue and groove” joint to restrict movement.

C U on the email, keith 