Bridge of Alcantara on the Tajo river, at Caceres.
Alzado este del Puente de Alcántara
Eastern elevation of the Bridge of Alcantara

This is probably the most important of Roman bridges at the world. In fact, its name Alcantara (Al Qantarat) means 'the bridge' in arab. That is enough to understand the value of this work. It was built between years 105 and 106 by Roman arquitect Caius Iulius Lacer on the Way that communicates Norba -today Caceres- with Conimbriga -today Condeixa-a-Velha-. Therefore it is not an access to a city.
It is composed by six archs that imply a distance of 214 m. on Tajo river. They are secured by five pillars and two supports at its ends.
Medidas del Puente de Alcantara
Measures of the Bridge of Alcantara

Its measures are really great: 48 m. high at its top: two central archs. Light of these archs is 27,34 m. for the 3rd and 28,60 m. for the 4th: they let the water run in the usual way. Prior and next archs are 2nd and 5th; they are 22,5 m. At last two extreme are 1st of 28,6 m. and 6th of 14m. These measures are not casual. They come from the necessity of saving a deep river with huge increases of its waters volume. The archs have two files of voussoirs: the upper is the lesser.
Rectangular pillars are about 12,20 m. x 8,3 m. and have triangular detached cutwaters of 8,3 m. at the basis and 7 m. each one of its other sides, forming a pentagonal shape. They are directly set on the slate rock that was made flat in order to support ashlars in a right way.
The roadway is 8 m. wide: 6,70 ms. for walking space and 1,30 ms. for both little walls.
Alzado del Arco de Triunfo del Puente de Alcántara
Elevation of the Triumphal Arch in the Bridge of Alcantara
At its center on the roadway there is a one gate Triumphal Arch that has been restored many times. It is 13,15 m. high with a rectangular plan of 11,5 m. x 2,60 m. It is supported by the central pillar of the construction. On it there are two marble plates: on one there is an inscription with the date of construction and its devotion to Trajanus Emperor:
"To Caesar Imperator, son of divine Nerva, Nerva Traianus Germanicus Datius, Maximus Pontifex, Tribunitia Potestas for the 8th time, Imperium for the 5th time, Pater of the Patria".

Other plates around the northern side of the arch would probably include names of municipia that colaborated with this construction. Today we keep other inscriptions dealing with different deeds. One, on Carlos I Age, shows a double-headed eagle and crenellations:
"Carolus V Imp/Caesar Augusto, hispaniarumque, Rex Hunc Pontem bellis et antiquitate ex parte diruptum ruianqueminatem instaurare iusit, anno domini MDXLIII, imperi sui XXIV, regni vero XXVI"

Another one was its dismantelation and restoring at 1858. It was again recorded on a new inscription:
"Elisabeth Borbonia hispaniarum regina, norbensem potem antiquae lusitaniae, opus iterum dello interrruptum, temporis vetustate pene porlapsum retituit aditum utrimque amplificavit, viam latam ad vaccaeos fieri iussit anno domine MDCCLIX"

Puente de Alcantara
General view
Arco triunfal del Puente de Alcantara
Triumphal Arch
(Bank of Images from National Center of Information and Educational Communication)

Construction of the bridge is really outstanding with aslars of padded granite -opus cuadratum- fit without mortar with the technique of rope and torch: with a regular frequence some bricks are perpendicular to the rest in order to give more solidity to the whole construction. Often, they are joined by metalic staples "milano tail", specially at the lower part of the pillars. Total highness of the bridge is 57 m. when we do not add 14 m. from the Triumphal Arch. Several military actions suffered along its existence has made that part of the archs were rebuilt, specially last two archs: 5th and 6th. They are not now the original archs.
Puente de Alcantara Puente de Alcantara
Old drawnings of the Bridge of Alcantara

At the southern side -left bank of the river- there is a little temple in altis. At its dintel an inscription let us read the architect's name -Caius Iulius Lacer- and the words "who will live so much as the world would live".
At the other side, the northern one, there is another square plan building: the Gold Tower, an instance of the defences once built.