Quoted from this website:

Since the founding of the city in 1158, this square has been the center and living heart of Munich. Jousting tournaments were held on this site in the Middle Ages; today, street performers and musicians draw the crowds' attention. The Mariensaule (St. Mary's Column) at the center of the square was erected in 1638 in gratitude for the preservation of Munich and the Bavarian town of Landshut during Swedish occupation.

Our tour guide mentioned that all official distances in Munich are measured from this column. The next photo in this collection is a closeup of the golden statue of Mary atop this column.

Marienplatz - St. Mary's Column
Marienplatz - St. Mary's Column