Piesport was located on the antique Trier-Mainz arterial road which later also became known as the Ausoniusstraße. The Roman troops used it to march on and also for sending supplies. There were milestones or league stones along the sides of these roads to mark the distance to the next most important settlement or town. At this time this was Augusta Treverorum (today the town of Trier) which was the capital of the west Roman empire in its heyday.
Since the time of Caesar Augustus, these stones and their inscriptions have also been used to record what the respective leaders have achieved. The roads can be dated based on the names of the reigning leaders.
One of these league stones was found to the north of Piesport in 1921 alongside the Roman road. The stone was erected in 213 AD during the reign of Caesar Caracalla and stands 18 Gallic leagues from Trier. A Gallic league corresponds to approx. 2.222 km, therefore 18 Gallic leagues are around 40 km. Caracalla was the byname of the Roman Imperator Caesar Marcus Aurelius Antonius (211-217 AD).
Translation of the inscription:
Caesar Marcus Aurelius Antonius, the pious, happy and exalted One, the mighty victor of Parthia and Britannia, pontifex, plebeian tribune for the 2nd time, consulate for the 3rd time, brave and great prince, pacifier of the globe, rebuilt the bridges and roads that had been destroyed by age, 18 leagues to Trier
You can see a replica in front of you - the original stone is on display in the Rhine State Museum in Trier.