Tal-y-Cafn Bridge
This is the only road bridge over the River Conwy between Conwy and Llanrwst.
The present Callender-Hamilton Bridge replaced an 1897 lattice girder bridge, and dates from 1977-8. It was assembled through and around the old bridge. Once completed, the new bridge was lowered onto the piers by cutting away piece-by-piece the old bridge.
The bridge also carries water in a pipe from Llyn Dulyn and Llyn Melynllyn in the Carneddau mountains to the coastal town of Llandudno.
The above information is condensed from the Wikipedia entry for Tal-y-Cafn.