We have no definite dates for the building of the Calmindon, but it was certainly raised in the time before the betrothal of Aldarion and Erendis, which places its construction within a few years of II 858. We cannot be sure how long it stood on Tol Uinen, but it might conceivably have survived until the Downfall of Númenor in II 3319 (nearly 2,500 years later) in which it would unavoidably have been destroyed.

We have no map showing exactly where the Calmindon stood, and all we're told about its island of Tol Uinen is that it lay somewhere in the bay of Rómenna. This was a narrow bay much used by ships, so presumably the island was in one of the wider parts of the channel where it would not interfere significantly with the waterborne traffic of the bay. This is the reasoning behind the location shown on the map, though in principle the island might have stood at any point within the bay of Rómenna.