One Tree Hill and Cornwall Park are joint together. A must do in Auckland, New Zealand! It has beautiful grounds with the coutryside feel and it is so relaxing to walk to the summit of One Tree Hill or also called Maungakiekie. One Tree Hill is a dormant volcano. It is a 182-metre (597 ft) volcanic peak in Auckland, New Zealand. It is an important memorial place for both Māori and other New Zealanders. The beautiful Cornwall park adjoins One Tree Hill Domain. It's a great place to go for a picnic or a day trip with your family and friends.