The town is located north of the Harz mountains approximatively 123 meters above sea level. The nearest mountains reach 181 meters above sea level. The biggest part of the town is located in the western part of the river Bodes bed. This river comes from the Harz mountains and flows into the river Saale and further into the river Elbe. The towns area of inner Quedlinburg is about 78.15 square kilometre, since the incorporation of 3 towns it grows up to 141.85 km².
The castle and the cathedral still towers above the city the way they dominated the town in early Middle Ages. The cathedral is a prime example of German Romanesque style. The Domschatz, the treasure containing ancient artefacts and books, was stolen by an American soldier and finally bought back to Quedlinburg in 1993 and is again on display here.