BENCHMARKS continued
Another example of two for the price of one. This pair are on the north-east corner of O'Donovan Rossa Bridge on the River Liffey. The 25" maps indicate that there should only be one there.
Below: The 'marks on O'Donovan Rossa Bridge. Surprisingly neither has the 'level' cut atop it. Someone has identified the lower one by daubing the letters BM on the pavement nearby.
Above: O'Donovan Rossa Bridge looking towards the Civic Offices. The 'marks are on the corner of the bridge.