We have no specific information about the building of the Harlond, but it seems reasonable to date it to approximately the same time as Minas Anor, the city it originally would have served.

In theory, though, the Harlond might have predated Minas Anor by some time. We know that the Númenóreans had established Pelargir on Anduin much earlier, in II 2350 (predating Minas Anor by about a thousand years), and so the Harlond might originally have been another minor port built on the Great River at about the same time. On this line of reasoning, Anárion would have chosen to build his city where he did because of the convenient pre-existing port, rather than building the port to service Minas Anor. On the whole, this seems a less likely possibility, but lacking more detailed information, it would not be impossible.

Exactly how the docks related to the wall is not entirely clear. The text of The Lord of the Rings (The Return of the King V 1) tells us that the wall ran along the edge of the river at this point, and that the Harlond was 'beneath' it. In his extended index, Tolkien also states that the Harlond was 'within' the wall. Of course the docks and quays on the river must themselves have been outside the wall, so presumably some kind of gateway led from the landings into the port itself, though the exact arrangement is nowhere described.