This historical monument was built around 1200AD by the eleventh Tu’i Tonga named Tu’itātui. This ruler had great power and prosperity to enable the construction of this lasting monument. The two vertical stones are about 5m high, 4.25m wide and 1.4m thick, and weigh between 30 and 40 tonnes each.
The lintel stone is 5.8m long, 1.4m wide and 0.61m thick. There have been many speculations about the purpose of the Ha’amonga. Some theory assumed that it is a gateway to a royal compound while others thought it resembles the ancient Celtic monuments of the Stonehenge.
In May, 1967, the late King Taufa’āhau Tupou IV proposed a new and more meaningful explanation. He offered that the notch carved on the top lintel may have had some significance in the lunar calendar and served as a guide for establishing the beginning of a New Year. In the months that followed, surveyors checked and found that as the sun rose on the shortest day of the year, the bearing taken matched perfectly with one of the Tropic of Cancer and the other to the Tropic of Capricorn. This would appear to confirm that the two points of the rising sun on the shortest and longest days of the year. On the 13th of May 1972, his majesty, the late King Taufa’āhau Tupou IV declared the Ha’amonga ‘a Maui a National Park protected area