In 1820, just a few months after King Kamehameha II and Queen Regent Kaahumanu had broken the kapu system at Ahuena Heiau, the first missionaries to land in Hawaii arrived on the brig Thaddeus and received the royals’ permission to preach. Within a few years a thatched-roof structure had risen on this site, on land donated by Gov. Kuakini, owner of Hulihee Palace, across the road. But after several fires, Rev. Asa Thurston had this massive, New England–style structure erected, using lava rocks from a nearby heiau (temple) held together by coral mortar, with gleaming koa for the lofty interior; the 112-foot steeple is still the tallest structure in Kailua-Kona. Visitors are welcome to view the sanctuary, open daily, and a rear room with a small collection of artifacts, including a model of the Thaddeus, a rope star chart used by Pacific Islanders, and a poignant plaque commemorating Henry Opukahaia. As a teenager, the Big Island native (known then as “Obookiah”) boarded a ship to New England in 1807, converted to Christianity, and helped plan the first mission to the islands, but he died of a fever in 1818, the year before the Thaddeus sailed. (In 1993 his remains were reinterred at Kahikolu Congregational Church, 16 miles south of Mokuaikaua.) On most Sundays at 12:15pm, following the service, Mokuaikaua Church hosts a free history talk.