The Heidengraben offered its residents a number of advantages: It was close to very fertile land, 800 hectares of which were actually inside the outer wall. There was plenty of fresh water nearby, a rarity in the uplands of the Swabian Jura due to its permeable geology. It was located close to important long distance trading routes, including the Danube and Neckar and the Albaufgänge (passes) connecting the two rivers. Immediately beneath Heidengraben was the Lenninger Tal offering access to Lake Constance (and later the site of a Roman road). The oppidum's inhabitants thus were well placed to profit from the trade flows passing through.: