Pu'u o Mahuka Heiau
This historic landmark is nothing more than a series of rock walls now, but 250 years ago it was a major temple on Oahu. This heiau (temple) is considered a luakini heaiu, in which sacrificial ceremonies, and even human sacrifice, were performed to help ensure success in wars. This 400-year old temple was built with rocks hauled from Waimea valley below.
After King Kamehameha conquered the island of Oahu, he took over this heiau. But in 1819 after Kamehameha’s death, his son Kamemahema II, abolished much of the traditional religious system and ordered the destruction of all heiaus in Hawaii, including this one. So what you will see are the remains of the once great Pu'u o Mahuka heiau.
This site is worth stopping at, however, for more than just the history. From the heiau there is a stunning view of Waimea bay and the Waimea valley below. You will have an incredible vantage point of the Waimea river, running from the back of the valley to the river mouth at Waimea Bay.
There is also a small walking path around the heiau if you want to get a bit of exercise while you soak in the surrounding beauty.