The Murerplan of 1576 Zürich was continuously inhabited since Roman times. Political power lay with the Grossmünster and Fraumünster abbeys during Medieval times, until the guild revolt in the 14th century which led to the joining of the Swiss Confederacy. Zürich was the focus of the Swiss Reformation led by Huldrych Zwingli, and it came to riches with silk industry in Early Modern times.