2011:197 - THE FORECOURT, LEINSTER HOUSE, KILDARE STREET, Dublin

The construction of a new heating pipe in the forecourt of Leinster House, fronting onto Kildare Street, gave rise to a monitoring programme, which was carried out in December 2011. Leinster House was built by the duke of Leinster in the mid-18th century and was the city residence of the family until 1815. Taken over at this time by the Royal Society of Dublin, the house and garden were subsequently purchased by the state and it has housed the Oireachtas or Irish parliament since 1922.
The house is set back from the street and is accessed via a large open forecourt. The trench was located at the southern end of this forecourt and ran east–west, extending past the front of the National Museum of Ireland. It measured just over 50m in length and was 0.6m in width by an average 0.7m in depth, terminating in the new glass reception building attached to the Porter’s Lodge at the western end. At the eastern end the pipe was tied into the existing building on the eastern side of the National Museum of Ireland.
The excavation of the trench revealed that this area was in use before Leinster House was built in the mid-18th century, with evidence of dumping of household refuse and demolition rubble producing 17th-century pottery. Thus, although the cartographic sources indicate that Leinster House was developed on a greenfield site, the archaeological evidence suggests that this part of the city was in use, possibly being the site of flimsy structures that have left no trace; similar evidence of brick buildings not represented cartographically were found a short distance to the north-east outside the Front Gate at Trinity College (Excavations 2002, no. 587, 98E0150).
One of the most important findings was the discovery that elements of the forecourt survive intact, buried beneath the ground. The forecourt space was originally defined by a pair of opposing curving screen walls, which extended from the elaborate gate (with pedestrian and carriage entrances) facing Molesworth Street to the colonnaded walls on either side of Leinster House. The site of the original southern screen wall is now occupied by the National Museum of Ireland, which was built in the 1880s on the site of the former stable-yard attached to the house. During the 1880s the screen wall was demolished and the forecourt shortened on the southern side.
The foundations of the southern screen wall were found at the western end of the trench, where it curved around to meet the gate, lying almost 0.7m below present ground level. This wall was constructed of limestone and measured 0.65m in width by at least 0.4m in depth; the blocks were long and narrow, measuring 40mm by 100mm. The wall was sparingly mortared with a hard dark grey mortar and the wall had no rubble core. The remains of a small stone-lined drain, measuring approximately 0.25m2 and roofed with thin slate, was noted at the base of the wall on the eastern side.
A second significant feature was a junction of two large stone drains in the middle section of the trench forming part of the drainage system for Leinster House. The drains were constructed wholly of limestone, measuring internally 0.4m2 and lying 0.6m from present ground level, presumably draining to the west downslope towards Kildare Street. This large drainage system is contemporary with Leinster House and it highlights the importance of water management in Dublin, where groundwater is always an issue. An elaborate drainage system was required at Leinster House to deal with the massive volume of water draining naturally from the high ground to the south and west, down towards Trinity College and ultimately the River Liffey. The college has similar drainage issues and these are cartographically represented on Rocque’s map of Dublin, dated 1756, which depicts a network of canals in what are now the playing fields, just north of Leinster House.
The drainage system was sealed by an extensive phase of cobbling found almost throughout the trench and this represents either the original 18th-century surface of the forecourt or the remains of a walkway along the inside of a curving screen wall. This surface was composed of very distinctive limestone ‘egg-shaped’ stones set vertically and lying 40–50mm below present ground level. The cobbles were large, between 100mm and 200mm in diameter, and set upright, the upper end forming the surface.
The final significant feature located during the monitoring programme was the remains of some sort of brick structure found at the western end of the trench, south of the gate. This wall, running east–west, was not excavated but lay just 0.3m below present ground level, sealed by plastic, suggesting that it was previously exposed. The type of brick suggests that it can be dated to the 18th century and it is probably all that survives of a brick latrine in this location, marked on Richard Castle’s original plans as ‘Dung hole’. The exposed wall is likely to be the northern wall. The latrine fill was very distinctive, a dark brown organic fill with a large amount of animal bone, shell, cinders, ash and fragments of charcoal. This also produced a number of ceramic pottery sherds, dating from the 18th century, mostly blackware and earthenware. The latrine was probably demolished in the 1880s, when the National Museum was constructed. It was subsequently sealed by a layer of modern cobbles.

28 Cabinteely Close, Cabinteely, Dublin 18.