The Limmat is one of at least two rivers that drain Lake Zurich and that run through the center of the city. The old town was built along the banks. On the left is the vibrant student/hippy part of the old city. The close cobblestone streets are lined with trendy shops, bars, restaurants, and strip clubs. The other bank of the river is where all the upscale shopping is. The border of the right bank part of the old town is the Bahnhofstrasse - the railroad street. Every town in Switzerland has a Bahnhofstrasse I imagine. It's sort of like Main Street here in the US.