Some of the practices seem a bit extreme to us now, for example the fact that some of the animals sacrificed to the gods were people and, seeing the islands had a big reputation for cannibalism, it seems probable that the feasts included the flesh of those sacrificed. These Maraes would have been decorated with carved wooden banners - many of which marked a human sacrifice.  It would also have been covered with skulls. Some from the sacrificed, but mostly the skulls of previous chiefs, warriors and other revered forefathers. The used to desiccate the bodies, leaving them out in the sun and oiling them with coconut oil until they dried out, then they would bury them a while, dig them up when they had rotted and bring the skulls to the Marae. 

In that way the Marae was a place where everyone could know who they were, where they belonged, both in the past and in the present. Some Maraes were for a particular family, some a profession, like fisherman or warrior, some for a nation or tribe. They connected you with those around you and those who had been before you.

And they spread out to the other islands, connecting them too. Each Marae on a new island had to incorporate a stone from Marae Taputapuatea even those as far away as the Cook Islands and Hawaii. Those on the new islands could still be in touch with where they came from, with their ancestors.

It was a special place to visit, knowing how many feet had stood in the same place for so very many years, how significant this ground was to so many generations of people. All around the dark stones are trees, they provided the wood for the carvings and they were home to the many birds that would stay around for the pickings from the sacrifices. The people believed the birds were the embodiment of spirits, sustained by the sacrifices.

Interestingly, The Essex, a whaler that was rammed by a whale and sunk, inspiring the Moby Dick story, had a number of survivors left in the small boats they used to harpoon whales in. They knew the nearest land was the Polynesian islands but they were so afraid of cannibals that they headed off in the opposite direction. As a consequence, those in the boats that made it to land had to resort to cannibalism to survive the journey. You're dammed if you do and you're dammed if you don't...