A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle. Designs of bridges vary depending on the function of the bridge and the nature of the terrain where the bridge is to be constructed.

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Le pont Luíz I est l'un des nombreux ponts de la ville de Porto. Appellé par la population locale "Ponte Dom Luis", c'est aussi le plus connu et un des plus anciens. Ce pont relie la ville de Vila Nova de Gaia à la ville de Porto.

Il a été construit entre 1881 et 1886 par l'ingénieur Teófilo Seyrig, un disciple de Gustave Eiffel qui avait déjà participé à la construction d'un autre pont de Porto : le pont Dona Maria-Pia.

Il a été inauguré le 31 octobre 1886 par le roi du Portugal Dom Luís I.

Il est composé de deux étages de 8 mètres de largeur chacun. L'étage supérieur mesure 395 mètres de long alors que l'étage inférieur ne mesure que 174 mètres.

Actuellement, l'étage inférieur est réservé aux voitures et aux piétons. Alors que l'étage supérieur est utilisé par le métro qui fait la liaison entre l'un des plus grands hôpitaux de Porto (Hospital de São João) et la mairie de Vila Nova de Gaia(ligne D du Métro de Porto).

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Bronze is any of a broad range of copper alloys, usually with tin as the main additive, but sometimes with other elements such as phosphorus, manganese, aluminium, or silicon. It is strong, tough and has myriad uses in industry. It was particularly significant in antiquity, giving its name to the Bronze Age. That name, in turn, is perhaps ultimately taken from the Persian word "birinj," meaning "copper".

A cannon is any large tubular firearm designed to fire a heavy projectile over a long distance. The cannon is the archetypical form of artillery.
Cannon comes through Old French from Old Italian cannone, ultimately derived from Latin canna—a tube. The Latinised word canon was used for a gun since 1326 in Italy, and 1418 in England. Bombardum, or "bombard", was earliest used for "cannon", but from 1430 it came to refer only to the largest weapons."Cannon" serves both as the singular and plural of the noun, although the plural "cannons" can also be used. The term can apply to a modern day rifled machine gun with a calibre of 20 mm or more (see autocannon).

Cannon also refers to a large, smooth-bored, muzzle-loading gun used before the advent of breech-loading, rifled guns firing explosive shells. Although a variety of such guns are commonly referred to as "cannon", the term specifically refers to a gun designed to fire a 42 lb shot as opposed to a "Demi-cannon" (32 lb), Culverin (18 lb) or Demi-culverin (9 lb).

When on board a warship a cannon is called a gun, while a cannonball is a roundshot.