A moot mound was a mound with a flattened top used by the Saxons as a meeting place. Probably the important guys stood on the top with rank and file gathered around. Some were made by adapting existing round barrows. They are often found on modern maps as mutlows ( mut = moot and low or hlaw is Saxon for a sacred hill or mound) Here they would resolve local matters, proclaim laws and dispense justice. In pagan Saxon days, the local chief was also the religious leader - the "godi" . Later, these early meeting places and law courts went inside buildings and the moot mounds were then only used as place of execution. They survived as gallows hills.
Open air law courts and seats of government were a feature of Germanic societies Tynwald on the Isle of Man is really a moot mound and the famous Thingvellir in Iceland was a massive open air parliament.