Originally in baroque form, the square was modernised by Elector Clemens Wenzeslaus of Saxony, who also had the Koblenz Castle built. The square received its name in 1468 "uff dem Plane", before that it was known as "Forum carnium" in 1339.

The south side of the square was largely destroyed during the Second World War, so that no historic buildings have been preserved here. The fountain in the middle of the square supplied the citizens of Koblenz from 1806 with drinking water from the Metternich water pipe, which was built for the Electoral Palace. The French builders used stones from the destroyed She Schönbornslust Castle and the fountain bowl from the Carthusian monastery of Beatusberg. In the northern part of the square a part of the baroque buildings from the 18th century is preserved. The city commandant's office with the flight of steps was the official residence of the fortress commandant of Electorate Trier. The building with the arches and the town commandant's office were used as a fire station from 1911 to 1973. The soprano Henriette Sontag was born in 1806 in Koblenz at the "Plan" and appeared at the age of six in children's roles, later worldwide. With her musical skills she was able to become a Royal Court and Chamber Singer. A marble plaque on her birthplace commemorates the world-famous daughter of the city of Koblenz.