saint marys bridge

While it was scarcely ever possible to ford the river here, it would still have been feasible to span it even with a primitive bridge at an early date. The river, entering the town from the west is almost 600 feet wide, narrowing at this point to only 110 feet, before expanding again to 450 feet in the docks area. The town grew around this crossing, which opened up a transport route north and south, and the Harbour below was developed to accommodate seaborne trade.

The early Bronze Age settlers in the Boyne Valley, and the later groups of Celtic peoples who populated the areas surrounding Drogheda around 900 BC probably entered Ireland by this route. Ptolemy, the Egyptian geographer, delineated with fair accuracy the course of the Boyne, which he called Buvinda, in his map of Ireland drawn up around the end of the 2nd century AD. The Vikings who made a settlement here on the south bank had, in 837 AD, according to the Annals of the Four Masters "60 of their ships in the Boyne mouth that year".