The Opunohu Valley, climbing from the bay up toward the Belvedere, contains the densest cluster of pre-European Polynesian ceremonial sites on Moorea — and one of the most accessible in French Polynesia. Marae Titiroa, just below the Belvedere, is a large rectangular ahu (altar platform) of dressed basalt with carved upright slabs marking the priest's seats. A short walk on a marked forest path connects it to several smaller marae, an archery platform, and the foundations of council houses, all under tall māpe chestnut trees with their fluted trunks. The site is in active use for cultural ceremonies and was a major centre of authority for the western Society Islands in the seventeenth and eighteenth centuries. Free to visit; allow an hour for the loop.