Here is a translation of the description on this photo:
http://www.flickr.com/photos/gustavo-adolfo/4211337347/
The Marquis de la Serna bridge named in honor of Felix Maria Messina, who was Governor of Puerto Rico from 1862 to 1865. It was the first metal bridge built on the island, and the only laminated iron arch that exists today. The iron items were brought from France. The bridge is segmented arches are similar to the Arcola bridge in Paris. The structure is located 24 feet above the river level.
The bridge was assembled by Isidoro Abarca, founder of the Foundry Abarca, was mounted on the same anterior bridge abutments built of masonry and wood. Part of the road between Cataño and Bayamón, a major route between the island of San Juan and agricultural lands in the west and south. Between 1881 and 1900, the bridge served as part of the railway train from the west. For this reason, two of the arches strengthened in 1881.