A marae's defining feature is the ahu, a raised platform, usually of stone, set at one end of an open court that is itself walled, paved or otherwise marked off from ordinary ground. Patrick Vinton Kirch's archaeological survey of the Pacific describes marae ranging from small single platform structures serving one family to vast stepped and terraced complexes, built without mortar from fitted or piled stone, that organized the ceremonial life of an entire district or island. Unlike the roofed temple architecture of much of the world, a marae's ritual space is open air, and its architecture is defined by what it excludes and demarcates rather than by what it encloses.
Construction and use followed local custom rather than one Pacific wide standard: some marae included carved images, upright stones representing gods or ancestors, or ovens for offerings, while others were austere platforms with almost no additional structure. What is common across the region is the underlying logic, a bounded, elevated, deliberately non domestic space set aside for contact with gods and ancestors, distinct from a heiau in name only, where Hawaiian tradition uses that separate term for the same functional structure.