Roman Wall, Grenoble
The Roman wall was built between 286 and 293 AD by order of Emperors Diocletian and Maximilian around the new city of Gratianopolis that replaced the old Cularo. The wall was 8 meters high and was elliptic. It was defended by about 40 half cylindrical towers. Two entrances "Porte Traine" and "Porte Viennoise" gave access to the city.
The Roman wall of Gratianopolis was made with a core of reused stones and covered with adjusted free stone. Most of the cover of free stones has disappeared along the centuries but though unimpressive, the old core is still very strong, thanks to the quality of the concrete used by the Romans
Most of the Roman wall of Gratianopolis still exists but is completely hidden as it is included in houses and forms a wall for the ground level, holding several stories of housing. Several towers still exist but can hardly be seen in the entanglement of old houses in the very city center. When streets have been open, it has disappeared and its memories remains thanks to iron nails sealed in the ground