Mt Eden (Maungawhau) is one of the most prominent volcanic cones remaining in the Auckland region. Erupting about 15,000 years ago from three overlapping scoria cones, it formed a huge scoria mound with a central crater from the last eruption. Lava flowed out from the base of the mound, and in some places the lava is more than 60 metres thick.

Maungawhau was a significant fortified pā, large enough to provide refuge for several hundred people. Extensive earthworks modified the steep upper slopes of the cone.