Follow the road for just under a mile until the canal swings to the southwest leaving the road, which has been a constant companion since the Leinster Aqueduct. The 18th lock may seem like any other but it has a special significance - it is the last step to the summit level of the main line of the canal. From this stretch, 279 feet above the old Ordnance Survey sea-mark in Dublin Bay, the headwaters of the canal divide to the east and the west. The buzz of racing engines at the nearby Mondello motor racing track can often be heard forming a contrast to the otherwise quiet ambience of canal and farms After the 18th lock the towpath continues into a pleasant flat grassy path way along the water’s edge which is over- shadowed by high banks and scrub. On passing under the next bridge - officially titled Burgh Bridge but invariably known as the Cock Bridge - the character of the walk changes sharply for the better. The towpath cuts through the Hill of Downings and on to Bonynge or Healy’s Bridge. In high summer and autumn this particularly delightful stretch is luxuriant with blackberry bushes. Gatelodge at Landesnstown House Canal bank fishing competition stand marker. 27 THE GRAND CANAL