Unfortunately and from what I know , the Auckland Harbour bridge climb can only be done during the day as that would be a great place to take a photo at sunset.
The Sky Tower is one place that comes to mind being it's open til late.
Another thing you could do is hire a boat or take your boat onto the harbour and take a photo of the sunset with the Harbour bridge.
My favourite place is at the top of Mount Eden...It can be a wee walk from the car, but it's one of those places where you feel like you are in the country. Your can lie down in the grass and stare up at the stars at night. It's pretty special
2022
