2001:397 - DUBLIN: The Monument of Light, Nelson’s Pillar, O’Connell Street, Dublin

Ian Ritchie Architects won a competition held by Dublin Corporation in 1998 to commemorate the millennium. Their controversial design, the Monument of Light, consists of a 120m-tall spire which will be illuminated at its point. A legal challenge to the monument resulted in an EIS, undertaken by Annaba Kilfeather of Margaret Gowen & Co.

As the foundations of the new monument will occupy the same location as the foundations of Nelson’s Pillar, pre-construction testing was recommended by the city archaeologist to determine the extent of the surviving remains. When it was ascertained that the foundations survived intact, a licence was applied for to supervise their removal as an archaeological exercise. The excavation took place throughout September and during the first week of October 2001.

A foundation stone for the monument was laid on 15 February 1808 by Charles Lennox, duke of Richmond and the lord lieutenant of the time. The doric column was designed by the Board of Works architect Francis Johnston (1760–1829) and the Portland stone representation of Nelson was executed by Thomas Kirk, RHA (1781–1845). The original entrance was underground, but in 1894 a porch designed by G.P. Beater, MRIAI, was added to allow direct access from the street.

The Pillar was blown up on the night of Easter Monday, 8 March 1966, supposedly by a dissident Republican element. The remaining stump was demolished by the Irish Army by means of a controlled explosion and the plinth was removed by Dublin Corporation’s Dangerous Buildings Department.

The earliest deposits recorded on site consisted of natural silts and gravels. These were recorded in the eastern section of the excavation at 2.73m OD, prior to the insertion of shoring, where they had been initially cut by the 17th-century cellars of the Henry Street structures. The truncated gravels were examined at the base of the Pillar foundation at approximately 1.42m OD, where they were found to be sterile. There was no organic matter present at this level.
Sealing the gravels in that area examined to the east of the foundations was a deposit of semi-organic soil. This deposit was examined in an area measuring 1.2m by 2m and no finds were recovered. It was possibly introduced over the area at some point in the last third of the 17th century to consolidate or reclaim the mud-flats. Bernard de Gomme’s 1673 map of the city depicts housing along the high-water mark just to the east of the present location of O’Connell Bridge, but nothing to the north as far as the ridge of high ground rising from the lower end of Parnell Square. His Map of Dublin Harbour 1673, although drawn at a smaller scale, refers to the O’Connell Street area as ‘Marsh Ground’. By the publication of Charles Brooking’s map in 1728 the area had been reclaimed and built upon.

The second phase of activity recorded on the site related to the cellars of buildings on the southern side of Henry Street, close to the junction with Drogheda Street. Three arched cellars were truncated by the insertion of the Pillar’s foundations, two of which appeared in section. The eastern springer of a third (belonging to the house on the corner of Henry Street and Drogheda Street) was briefly exposed before shuttering was inserted.

The two cellars exposed were of differing widths, which correspond to the plot widths as depicted on John Rocque’s 1756 Exact survey of the city and suburbs of Dublin. The cellar of the second house on Henry Street was 3.42m wide and would have extended to a maximum height of 1.96m above a cobbled floor surface (the crown of the vault was probably broken when the buildings above were demolished c. 1790). The eastern springing wall of the cellar belonging to the third building on the street was not exposed in the section; however, a width of 3.14m was calculated on the basis of the maximum height of the vault, which was 2.02m above the cobbled floor level.

The walls of the cellars were of calp limestone rubble bonded in a rough lime mortar, with a thickness of 0.42m. The rounded vaults were in a hand-made red brick of various dimensions. The void between the vaults was filled with water-rolled cobbles with typical dimensions of 0.12m by 0.08m, which were bonded in a similar lime mortar to that in the cellar walls.

The cellars appear to have extended for approximately 4m out from the street frontage (as evidenced in the eastern section of the trench). The vaults survived for a further 2.7m to the south of the Pillar’s foundations, at which point they were presumably cleared by the Wide Streets Commissioners’ widening of what was now Sackville Mall, in the 1790s.

The fills of both cellars were quite different. The fill of the eastern cellar was mostly composed of rubble from the collapsed crown of the vault, which consisted in the main of loose fragments of red brick and mortar. Quantities of earthenware roof tiles recovered from this deposit would suggest that the building was roofed in this material at the time of its demolition. The rubble overlay a compact deposition of sooty soil, which appeared to be an in situ deposition in the cellar. This material measured from 0.29m in height (at the eastern side of the cellar) to 0.38m (at the western end) and contained the remains of most of a large North Devon gravel-tempered vessel and several bottle fragments, all of which date from the end of the 17th century. A fragment of a North Devon gravel-tempered ridge tile from this context would suggest that the building above was originally roofed in this material. There was, in addition, a deposition of mixed shells towards the bottom of the deposit. This material sealed an occupation deposit on the surface of the cobbles from which no finds were recovered.

Approximately 40% of the material filling the western cellar would appear from the tip lines to have been deliberately backfilled from the south. This material consisted of loose building rubble, which did not quite extend to the vault soffit. Several roof slates were recovered from this deposit. This sealed a more compact soil, which appears to have accumulated in the cellar over some time. Root action within this lower fill disturbed the position of the finds within the material, which had accordingly become relatively homogeneous. The soil matrix contained silty loam, and finds recovered included a considerable number of glass bottles, sherds of North Devon sgraffito, Staffordshire slipware and imported stonewares.

Little is known about this early development on the lands formerly belonging to the abbey of St Mary, which were granted to the Moore family, later the earls of Drogheda, in 1619. The area was set out in lots in 1682 and Marlborough Street, where construction began between 1700 and 1710, formed the eastern extent of the built estate. Charles Brooking’s map of 1728 depicts the grid pattern of the old Drogheda estate (since 1714 under the ownership of Luke Gardiner), and shows the enclosed slob lands east of the North Strand Road as being still liable to flooding.

The cellars recorded in the southern section of the trench certainly relate to the period of the first buildings on the site and belong to narrow, three-bay Dutch Billys, which probably date from the last decade of the 17th century. The buildings as depicted by Rocque reflect the disjointed approach taken throughout this early period of the city’s modern development, with unequal plot widths, differing plan types and serrated street frontages, their long plots extended to stabling fronting onto Princes Street. The plots to the west were encroached upon by the General Post Office in 1814.

The cellar fragments survived under the median of the extended Sackville Mall from the demolition of the buildings above in the 1790s until they were further disturbed by the insertion of the Pillar in 1807/8.

The enabling works for the Pillar are mentioned in the report of the laying of the foundation stone in the Freeman’s Journal. A paling was erected around the foundation trench, which, as has been outlined above, had cut through the surviving cellars of the three buildings at the corner of Drogheda Street and Sackville Mall. The construction cut itself was recorded on the eastern and southern sides, where it ran 0.14–0.26m from the face of the masonry. This would indicate that the Pillar foundations were constructed from the inside out.

The lower course of masonry was located at 1.42m OD, which was 3.45m below the level of the pavement. This consisted of a block of masonry, roughly squared at 6.6m. The edging blocks were better cut than the rubble used in the interior and were on average 0.8m by 0.5m by 0.4m. The interior blocks tended to be larger and rougher. The rough circular base of the Pillar itself was maintained down to this level at the centre of the foundation and had a maximum exterior diameter of 4.4m. A sherd of imported stoneware was recovered from the mortar below one of the blocks of masonry.

A void was maintained slightly off the centre of the Pillar base into which the foundation stone was lowered. The void was not formalised with dressed masonry and was 0.19–0.22m in depth. Its base was composed of the natural gravels onto which a rough mortar mix was applied.

The foundation stone of Nelson’s Pillar consists of a cut granite block with a rectangular cavity in its upper surface. The block measures 0.66m by 0.55m and is 0.3m deep. The cavity measures 0.41m by 0.25m and is 0.08m deep. In its centre is a second roughly cut cavity, 85mm by 35mm with a depth of 60mm. This is dovetailed, being longer at its base than the surface, and was used for lowering the stone into position with a mason’s device known as a lewis.

The main cavity was cut to accommodate a brass plaque that was placed into it and then sealed with rosin. The now-solidified rosin filled the lewis recess and created a thick sealant layer under, around and over the top of the plaque. The thickness of the rosin on the surface of the plaque varied from 1mm to 5mm, suggesting that it was poured as a liquid and not painted on. The plaque is 397mm by 245mm and 6mm deep. The upper surface was polished and engraved with an inscription eulogising Nelson and a list of the members of the committee for erecting the Pillar. There are six holes in the plaque, suggesting that it had initially been intended to screw it into position. The contents of the stone were finally protected with a lid of Portland limestone placed inside the granite cavity.

After the foundation stone was laid, the void within the Pillar appears to have been covered with a mixture of soil and silt. The void was maintained up through the column but not formalised in dressed masonry. At the second or third course of masonry, the column was keyed into the square foundation by masonry ties, 1.3–1.4m in width. They were located at the central point along the sides of the foundation and extended upwards at least to the level of the pavement and probably higher. The voids thus formed behind the corners of the foundation and within the centre of the column would appear to have been filled by loose limestone rubble with occasional fragments of lime mortar.

The masonry from the foundation was removed to the Dublin Corporation depot at Fairview and it will be reused in landscaping.

2 Killiney View, Albert Road Lower, Glenageary, Co. Dublin