The Luisenplatz in the 16th century along with the city walls. It changed in the 17th century as it was designed by a garden architect and a fountain got added in this reconstruction.
There are cafes and restaurants located around the square. Every year there are smaller town festivals, a part of Christmas market and more happening at the square.
Wikipedia https://sv.wikipedia.org/wiki/Luisenplatz,_Potsdam
Address 2 Luisenplatz, Potsdam 14471, Germany
Coordinates 52°23'58.06" N 13°2'49.813" E