2016:182 - National Gallery, Merrion Square West, Dublin 2, Dublin

In March 2011 the Office of Public Works began a major project of restoration and repair of the historic Leinster House complex, which included substantial works to the National Gallery, which is now completed, running from 2014 to 2016. The National Gallery, which was opened in 1864, is a Protected Structure (no. 5191) and the grounds contain two additional Protected Structures, the statue of William Dargan (5192) and George Bernard Shaw (no. 5193) both of which were protected during the works. The works included substantial restoration and repair of existing structures within the complex, most notably an underpinning progamme, which resulted in large-scale excavations within both the Dargan and Milltown Wings, and within the central courtyard. Outside the gallery, the former grassed area or forecourt fronting onto Merrion Square West was excavated out and a new subterranean Energy Centre was built, measuring roughly 33m in length (east-west) by between 25m and 38m in width by approximately 6m in depth (Plan no. 2566/11). The open area to the south of the gallery, between the gallery and Leinster House was also excavated for new services, all of which was monitored.

Cartographic analysis indicates that this area was undeveloped until relatively recently, although Merrion Square West (unnamed) was laid out by 1673. Charles Brooking’s map of 1728 shows the development of the area, with some of the land laid out in long narrow plots, orientated east-west, and some with houses fronting onto Merrion Square West (annotated Merrion Lane) but no buildings elsewhere. In 1756 the map by John Rocque records the rapid expansion in this area between 1726 and 1756. Kildare House (now Leinster House) has now been built (1745-8) and this had a grand formal garden fronting onto Merrion Square West, the remnants of which is now called Leinster Lawns. The garden is flanked on the northern side by three brick houses with stable buildings at the rear. Plans were also afoot to construct a large square, now Merrion Square. Kildare House, renamed Leinster House and the seat of the Fitzgerald family, was sold in 1813 to the Royal Dublin Society, the family moving to Carton Demense in Co. Kildare. In 1922 the emerging government of the Free State obtained Leinster house as a temporary government building but eventually purchased it. It is now home to the Oireachtas.

The need for a national gallery at Dublin was first proposed by William Dargan, the eminent railway engineer and, after much fund-raising, was finally opened in 1864.

Southern and eastern side

Initial excavations consisted of service trenches along the southern side of the gallery and these located deep deposits of clay, cinders, mortar, brick and rubble, reclamation layers that were found to extend throughout the site to depths of 2.5m, evidently used to build the ground level up in this location. A trench orientated north-south across the inside of the modern gate exposed post-medieval clay fills to over 1.1 in depth, banded with layers of brown clay, brick, mortar and shells but getting deeper as they extended west. All material was deliberately and systematically dumped in this area. The lower levels were mostly yellow and brown clays but some contained post-medieval pottery suggesting infill deposits to 4m in depth in places. This massive reclamation, dated to the 19th century, was found to extend right across the entire site, including the footprint of the new Energy Centre, and was presumably carried out at the time the gallery was constructed as a massive infilling project.

Monitoring also located the eastern end of a solid limestone wall that ran east-west to the south of the gallery and was evidently a boundary. It measured 0.35m in width by at least 1.3m in depth but was only faced on the northern side, presumably acting as a retaining wall. It was composed of large well-cut rectangular blocks at the upper level, irregularly coursed with rougher faced blocks at the base and mortared with a hard, white cement-like mortar. The continuation of this wall was found later during the monitoring programme extending for some distance along the southern side of the gallery with a number of granite piers at intervals along the northern side. This wall was left in situ.

East side, near front gate

The remains of some sort of pier were also found just inside the modern gate and 1.3m north of the boundary wall. This measured 1m square and was badly damaged on the northern side but with a narrow, similar wall 0.3m in width extending towards the gate. Like the boundary wall, this was also constructed of limestone, mortared with a distinctive yellow mortar and aligned with the southern pier of the modern gate, which evidently replaced it. A Victorian brick manhole was constructed between the wall and the pier, the western wall of which was exposed.

Energy Centre

Excavating the footprint of the new Energy Centre was done in a systematic way to allow for archaeological recording, with the entire footprint reduced by 0.3m at a time. The initial 1.5m was excavated, then excavation was halted to allow for secant piling. This piling then formed the shoring for the subsequent excavation. The only substantial structure during these initial works was a massive foundation of limestone at the eastern end of the forecourt towards the street frontage. This originally held a statue and represented a solid limestone block, 1.5m square, but which got progressively wider at the base, measuring 2.1m square by 2.8m in depth. This feature was retained and was not removed during the construction of the Energy Centre. The excavation initially stepped off the National Gallery frontage but exposed the 18th-century boundary wall along the northern side, where the adjoining houses abut the grounds. This revealed a wall that was only faced on the northern side and therefore was retaining the reclamation deposits within the forecourt. After the piling was installed, the remaining deposits up against the main frontage of the gallery were also carefully removed under the care of the Conservation Architect and this revealed the substantial wall foundations of the basement. Fragmented remains of earlier steps were also located and preserved in situ.

Milltown Wing

Within the National Gallery, work began on the underpinning in the basement of the Milltown Wing to a depth of 2m. A number of test-pits were excavated to establish the nature and extent of the deposits and these were positioned along the existing pier bases. These pits revealed the basement was cut into natural dark grey and tan brown sticky clays with stone, evidently natural ground. Subsequent excavation confirmed this although a number of brick drains were found at the eastern end, probably contemporary with the gallery.

A well was located in the north-east corner of the basement and work ceased to record this feature. This well pre-dated the gallery and had simply been sealed by the cellar floor. On exposure it measured 2m in diameter and 7m in depth and the water was pure, at 1.2m below the floor level. The upper 1m had no stone lining but after the well was pumped out, a stone lining was exposed, at 1.7m below the ground level. With the stone lining, the internal circumference measured 1.5m in width at the stone lining. The limestones were large, generally measuring 0.3m by 0.4m and there was no indication of mortar although it was difficult to see. The well was sealed with stone (804) and left in situ.

Dargan Wing

Underpinning was also carried out in the Dargan Wing to a depth of 2.2m, but 1.3m beneath the actual walls. This was deeper as the western end of the wing is at a higher level accessed by steps and there is no basement in this location. Initial test-trenches exposed the remains of sub-floor stone foundations in the form of small foundation walls beneath the pillars which extended out to the main north and south walls. These walls were exposed and recorded. Between the walls there were infill deposits of brick, mortar and rubble to approximately 2m in depth but the natural was a dark sticky boulder clay rather than the grey/black clay seen elsewhere, similar to the natural clay just inside the gate.  A strip of this infill material was left down the middle of the western end and is still in situ. Excavation and underpinning was also carried out in the adjoining room on the north, west of the courtyard, where similar dark grey clay was noted. At the eastern end of the Wing, within the basement of the main hall, underpinning established the basement was cut into natural clays at just 0.25m below the floor level of the basement.

Attenuation tank

A large excavation was carried out for an attenuation tank at the southern side of the Energy Centre, east end, in the area already tested for services in December 2015. This measured 8.2m north-south by 23.2m to at least 4m in depth. This excavation exposed more of the infill deposits as found elsewhere but also the southern boundary wall previously mentioned that was exposed for the full length of the excavation on the southern side thus extending for over 23m in length in this location. This can be associated with the earlier pier found just inside the gate along with what is likely to be the eastern end of the same wall. When exposed, this was found to be a retaining wall with a number of curious granite piers along the line of the wall.

28 Cabinteely Close, Cabinteely, Dublin 18