Our first North Shore stop was the Waialua Sugar Mill, a former sugar mill which closed about fifteen years ago and now houses several retail stores. It (with some aggressive colour timing) stood in for Mr. Eko's Nigerian village in the episodes The 23rd Psalm and The Cost of Living.
The mill also appeared briefly in the Sawyer-centric ep The Long Con.
The 23rd Psalm is one of the strongest season 2 entries, and the unique look of the soil and landscape around the mill helped sell the African backstory.
This structure, no doubt part of the sugar production process at one time, now sells various locally-made soaps and other items. I picked up a few gifts here.