It was the first bridge built over the Tagus in Portuguese territory, in 1861. It was considered, at the time, one of the largest and best railway lines in all of Europe.
The primitive bridge, whose structure rested on cast iron tubular pillars, of which only half rested on rock, had technical problems and had to be completely replaced.

The new bridge, whose foundations were the responsibility of the Eiffel House, was built between 1887 and 1890, laying the deck on masonry pillars.
In the 1980s, CP removed the bridge from rail traffic and built another one, parallel and sharing the same structure.
After rehabilitation and adaptation works, the bridge began, in 1988, to serve road traffic.
Having only one direction at a time, given the narrowness of the deck, and with several limitations to its use, namely by heavy vehicles, the bridge is saturated and in need of urgent replacement.

With its 494 meters in length.

Source: http://www.cm-constancia.pt/index.php/pt/visitar/patrimonio#ponte-sobre-o-tejo