It is modest enough to be easily overlooked, yet its purpose, at least according to local tradition, was entirely practical: it was built to be seen rather than entered, a navigational marker for the merchant ships of the man who had it constructed.

The tower stands on Horse Island in Castlehaven, and tradition attributes it to a figure named Somerville Large, who reportedly had it erected to guide his vessels safely into the harbour. The term belvedere, loosely applied to this kind of structure, usually describes a building or tower designed to command a view or to be visible within a landscape, and here the two functions may well have overlapped. A private landmark that served a commercial purpose, it sits at the intersection of landed ambition and working maritime life, a combination that was not unusual along this stretch of coastline, where merchant families with property and shipping interests shaped the landscape to suit both.