2.25 m thick, corresponding to a favourable ratio of rib thickness to clear span of only 1/32. The sandstone bridge was almost 9 m wide. Today, the two abutments with overhanging remnants of the arch vault are all that remain.

The Trezzo Bridge was not matched until the metal Wearmouth Bridge of the same span was built at Sunderland, England, in 1796. Longer masonry arch spans were not achieved until