If you happen to be thinking of demolishing the road bridge in Athlone at any time, please try to remove the foundation stone carefully, without breaking it, and look for a cavity.
Mr Rhodes, the principal Engineer of the River Shannon Improvement Works, having paid a visit of inspection to the bridge works of Athlone; a copperplate, with an inscription thereon, was deposited in a cavity in the foundation stone, which was laid on the 6th instant. The site on which the new bridge is to be erected is 70 yards up the river from the present bridge. The new bridge is to consist of three elliptical stone arches, each of 60 feet span, and 14 feet rise, and one iron swivel arch of 40 feet, to admit the passage of steam vessels of a large class.
The Galway Vindicator and Connaught Advertiser 27 November 1841
If you find the copperplate, do please tell us what the inscription says.
Irish waterways history 
Aside from the wonders of bridges past, bridges future are causing quite some controversy in Athlone at present:
http://www.westmeathexaminer.ie/news/roundup/articles/2014/10/02/4032877-getting-cycleway-across-shannon-causing-headache-for-the-planners/
I can see the difficulty. I’d be inclined to hang a cycleway off the railway bridge instead of the road bridge.
Limerick’s problem is that it has too much money for pedestrian/cyclist bridges, as Michael Noonan follows in the footsteps of his great predecessor Thomas Spring Rice, who persuaded HMG to build the current Athlone road bridge (and much else).
Bock the Robber suggests that the Limerick bridge could be built along the foundations of the weir; it would probably be a bad idea to interfere with the foundations of the much older Athlone weir (built courtesy of Mr Spring Rice’s efforts) by doing the same there.
I think I’m with Brian Leddin on the Limerick bridge. There is already a footbridge linking Arthur’s Quay via the Custom House moorings and the Potato Market with the area of St John’s Castle; with the proposed demolition of Sarsfield House, the route need not be locked off at night and a more sensible security system for boats could be devised.
Anyone mentioning Calatrava will be shot at dawn.
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