Designed in the style of ancient Celtic jewellery this large grass area lies on the site of the Black Pool or in Irish, Dubh Linn. In Celtic and Viking times the River Poddle, which supplied fresh drinking water and filled the moat of Dublin Castle, also formed a pool at this spot. The Vikings used this pool as a sheltered harbour for their ships. It is from the Dubh Linn pool that Dublin gets its English name.
The garden now serves as a helicopter-pad.