The 1,500-year-old Mo'okini Heiau, once used by kings to pray and offer human sacrifices, is Hawaii's oldest, largest, and most sacred religious site (and now a national historic landmark). The massive three-story stone temple, dedicated to Ku, the Hawaiian god of war, was erected in A.D. 480; each stone is said to have been passed hand to hand from Pololu Valley, 14 miles away, by 18,000 men who worked from sunset to sunrise. Kamehameha, born nearby under Halley's Comet, sought spiritual guidance here before embarking on his campaign to unite Hawaii.

An ancient priest named Paao arrived in the 11th or 12th century from Tahiti to find Hawaiian society in a state of anarchy. He did a nice job of restructuring society, but unfortunately he brought a gruesome tradition with him—human sacrifice. In front of the heiau there is a large lava slab with a dip in it that was the place where people were put to death to feed Paao’s hungry gods. This is not a place where one would necessarily want to commune with the spirits, but it’s a Hawaiian temple with a unique history. Some people who visit this heiau claim that an eerie atmosphere pervades the area unlike anywhere else.