Indicated — Esker South

King Johns Bridge crosses the Griffeen River 30m upriver of the 19th-century bridge annotated Esker Bridge (NIAH Reg. No. 11204023) on the 1837 ed. OSi 6 inch map. This partially ruined hump-backed masonry bridge crossing the river from SW to NE probably carried a medieval road leading to St Finnian's medieval church ruins (DU017-022001-) and graveyard (DU017-022002-) 100m to NE. According to O’Keeffe and Simington (1991, 134-6), the bridge is clearly marked on Rocque’s map as 'King John’s Bridge'. Esker was part of a demesne in the Liffey valley which Henry II annexed to the crown and which was organized under King John as a royal manor. The bridge probably fell into disuse between 1760 - the date of publication of Rocque’s survey map of the County of Dublin and the 1837 edition of the Ordnance Survey six-inch map when the road is shown as re-aligned and Esker Bridge constructed. D'Alton (1838, 660) recorded that 'by an act of 1771, Mr Vesey havinn agreed that the road from the new bridge over the Liffey, should be carried without any expense to the county through his estate in a certain line, whereby said road would b considerably shortened, it was enacted, that, as soon as the said new road should be finished, it should be lawful for Mr. Vesey to stop and enclose that part of the old road which lies on the west side of the little river Griffin'. Only a single central arch survives of the original triple-arched bridge, what survives is a partially intact central arch and accompanying piers, a short length of the NE arch and the demolished remains of the SE arch. The overall length of the visible remains is 7.7m and is 4.3m wide including cutwaters. The surviving central segmental arch is formed of narrow voussoirs set on edge rising from straight-sided piers. The keystone is wedge-shaped and was slightly too large to fit perfectly. The bridge spans an opening 2.1m wide and is approximately 3.8m in length. At its narrowest width it measures 0.8m surviving better at the upstream end to the SE where it measures 2.1m. The piers are composed of well-made coursed rubble masonry up to five courses high. In overall height the piers measure 1.5m from the river bed to the arch springing point with evidence for some rebuilding of on the inner edge of the N pier. Two triangular cutwaters project 0.5m upstream at 45 degrees each side the arch opening. Just beyond the intrados of the SE arch the imprint of a short length of wicker centering can be seen at the N side of the arch. Test excavations located 1.5m to the W of the bridge in 2003 under licence no. 02E1018 revealed a cut-limestone wall post-dating the bridge that was aligned N-W/S-E which followed the course of the Griffeen River (Kavanagh 2006, 170) References: Kavanagh, J. 2006 King John's Bridge, Lucan. In I. Bennett (ed.) Excavations 2003, 170. See attached Rocque's 1760 Map of County Dublin showing King Johns Bridge and Esker Church ruins See attached reconstruction of King John's Bridge by Jonathan Cully courtesy of the Society for Old Lucan Compiled by: Margaret Keane Revised by: Caimin O'Brien Date of revised upload: 14 March 2023