The artwork was craned into place at the Octagon under the watchful eye of a Downer employee.
Ko te Tūhono, by Ayesha Green, is a cast aluminium replica of the doorway into Ōtākou's wharenui Tamatea.
"It is a passage to our landscape, our life and the wairua we share with the harbour," Green has said.
"When you move through Ko te Tūhono, you are inside and outside, you are coming and going.
"As a monument to our tipuna and our tamariki, Ko te Tūhono transcends time and space."