Complex sentence: Dingwall Castle was once the biggest castle north of Stirling; on the town's present-day outskirts lies Tulloch Castle, parts of which may date back to the 12th-century building.
Split into simpler sentences: Dingwall Castle was once the biggest castle north of Stirling. On the town's present-day outskirts lies Tulloch Castle, parts of which may date back to the 12th-century building.