When the Romans occupied Lutetia (Lutèce), the future Paris, during the first three centuries AD, they consumed a lot of water. The dwells, sources, rain and river water was not sufficient. There were at least three public baths, whereof the Cluny Baths still visible were the biggest, and many fountains. A lot of clean water was important. At least one aqueduct was constructed, leading water from south of the city. It seems that it had a capacity of some 2.000 m3 per day. Compared to those days’ population, some 8.000 (?), it would mean that their per capita consumption was comparable to what we today use as water!
There are still a few things left from the Roman times, the most visible are probably the “Arènes”, the amphitheatre (see previous post) and the Cluny Baths (see previous post). The Roman Forum was to be found close to where you can now find the Panthéon (see previous post), but nothing is today visible.
There are some timid traces of the aqueduct outside the city, but there seems to be only one today to be seen within the city limits; the other few rests are underground and the aqueduct's way through the present city is rather clear, the red dotted line. The visible rests can be found just north of the Parc Montsouris (see previous post) - marked here by the little yellow circle - and were obviously found and brought to light when some modern buildings were constructed.
When looking a bit closer, you can see that the Romans already knew how to manufacture water resistant concrete, reinvented much later.
I wish you a nice weekend!