The largest collection of Maoi statues can be found at Rano Raraku. From this volcano, the statues were carved and shipped across the entire island. There is a park entrance where you have to show your ticket. Absolutely stay on the given paths!
Here you can see the 'quarry' from which the Moai were made. Many are still standing and some have already fallen over. You should have seen it; is really great and you can not get that close to moai otherwise.