The heart of the Altstadt is the elongated, pedestrianised Marienplatz, framed by sturdy towers such as the round Grüner Turm, with its lustrous tiled roof, and frescoed patrician houses, such as the late-Gothic, step-gabled Waaghaus. The 15th-century Lederhaus, with its elaborate Renaissance facade, was once the domain of tanners and shoemakers.