Duke Leopold VI of Austria about 1230 had the walled town of Laa laid out as a strategic outpost at the border with the Kingdom of Bohemia in the north.

His successor Duke Frederick the Warlike used it as a military base for his Bohemian campaigns, until he was finally killed in battle in 1246.

Nevertheless, the town's significance decreased over the following decades, it was devastated by the troops of Margrave Jobst of Moravia in 1407 and again in 1426 by Hussite forces.

According to legend, the later Pope Pius II (Enea Silvio Piccolomini) worked as a priest at the Laa parish church from 1442, actually he served as papal legate to the Imperial Diet and counsellor of Emperor Frederick III.

During the Thirty Years' War, the town was first occupied by Bohemian troops until the 1620 Battle of White Mountain, later by Swedish forces, who left Laa in a desolate condition.