2005:435 - DORSET STREET/GRANBY ROW, DUBLIN, Dublin

The site extends over c. 0.078ha, fronting onto Dorset Street and Granby Row. Prior to its demolition the site was occupied by the Wax Museum building. The site was previously occupied by a late 18th-century church – the Bethesda Chapel. An architectural survey indicated that only limited fabric related to the superstructure of the original chapel building survived within the frame of the Wax Museum building. On this basis, demolition of the Wax Museum was allowed to proceed.
A test excavation was carried out in October 2005 and substantial remains of a post-medieval structure were identified – most likely the substructure of the Bethesda Chapel.
Full excavation of the site was undertaken between 16 November and 12 December 2005. The results indicate that substantial remains associated with the substructure of the Bethesda Chapel were present at the site as well as vestigial remains of a Georgian terrace pre-dating it. This indicates that Scalè’s map of 1760 is accurate in showing a terrace of houses extending to the junction with Dorset Street; a minimum of two terraced houses would have been demolished to accommodate the construction of the chapel in 1789. The remainder of this terrace survives to the south of the site.
The substructure of the Bethesda Chapel occupied the majority of the site. It was defined by a substantial mortared stone wall which outlined the original footprint of the building (measuring 31.5m by 18.5m). The interior of the building was characterised by a dense complex of walls. In the front section of the building (at Granby Row) they defined a series of rectilinear and square cells; there is a direct relationship between these cells and the plan of the building illustrated on the first-edition OS map.
Vestigial remains of an extension to the existing Georgian terrace (a party wall and a coal cellar) were identified in the eastern corner of the chapel footprint. These remains had been partially incorporated into the substructure of the chapel. Associated with this was a rough mortared surface in the eastern corner of the chapel structure and also two wells.
Though the substructure of the chapel was quite substantial (most of the main walls were formed 2.5–3m below the original ground floor level), very little of it was utilised as a basement. Most of the footprint was deliberately filled in and sealed off with mortar. It is possible that the reason for this was technological; i.e. it was the only way to create the strength of footings required to support the chapel superstructure. However, it is also possible that this was a response to the prevailing conditions at the site during construction. The section of Georgian terrace demolished would have included a substantial basement area. Including the basement yard and coal cellars, c. 50–60% of each plot of the existing terrace is occupied by a basement level. It may have been more practical (and possibly safer) to expand the existing basement and then infill after the substructure was complete than to infill the terrace basements first. Certainly the excavation indicates that only a small section of the substructure was open and usable – the stairwell, plant room and corridor. It is likely that the plant room accommodated a furnace or dynamo – a cast-iron furnace was displaced and used to block up the doorway leading to the corridor.
While the section of the site along the Granby Row frontage (approximately one-third of the structure) was relatively well preserved, this investigation highlighted significant disturbance and disruption of the substructure in the remainder of the site as a result of the insertion of modern concrete supports during the 1980s.