The  large foreland of Magilligan developed after the last ice age and stretches out into Lough Foyle where a narrow and dangerous tidal channel exists between the Point and Greencastle in Donegal. Sea level would have originally covered this area to a shoreline at the foot of Binevenagh, as the  ice cap melted the land slowly rose and Magilligan appeared from below the waves. It is the largest accumulation of sand deposits in Ireland.   Benone Strand stretches from below Mussedun Temple at Downhill to Magilligan Point, a distance of over ten kilometres and one of the longest beaches in Ireland which provides excellent walking, it is also used for kite surfing and sand yachting.

The inspiration for these structures came from an encounter the Royal Navy had at Mortella Point in Corsica in 1794 when they tried unsuccessfully to take one with two naval ships. The shape and thickness made them resistant to cannonballs which deflected off the curvature, a multi-positional mounted cannon on the roof proved to be a very tough defence. Magilligan was used as the baseline measurement during the first large scale mapping of Ireland by the Ordnance Survey in 1827, the baseline was eight miles long and passed through three fixed circular triangulation stations. The work by Major General Thomas Colby achieved the highest level of accuracy at the time. It was remeasured in 1960 using electronic equipment and the new measurements differed from Major Colby's by only 1 inch.