bridge bridge spanish known roman arch bridge region spain ancient structure featured flattened arches span rise ratio earliest kind design assumed bridge erected early 2nd century emperors possibly guidance famous architect time long bridge served crossing point important north south connection western longest river peninsula presumably remained service numerous early modern reconstruction attempts spanish engineers failed ruins mainly found right river bank relocated original position reservoir created location road access historic bridge confused monumental bridge downstream spanned far mouth heart spanish province region modern motorway railway cross immediate vicinity historical importance crossing point northern southern spain building remains bridge moved original site meadow kilometers north close municipality contrast traces left neighbouring ancient bridge river classical period roman road later called important inner connection led provincial capital south river valleys north western passing major town terminal point north western spain main routes established successors military control peninsula exploitation rich spanish silver gold mines apart junction remains ancient bridges found road close fourth hills overlooking roman spanish established according customary distance intervals fourth total number sixteen history exact construction date unknown missing literary sources arches suggest built early 2nd century specifically reign emperors use arch form typical era rulers born southern spanish province known ordered restoration came power arches employed court architect notably greatest civil engineering achievement time rested huge concrete piers wars moving troops wide danube mention praise roman bridge leads evidence community called arabic small bridge existed temporarily probably indirect reference high rising bridge remains unknown bridge called local vernacular expression alludes legend bridge probably use time constituted border christian realm 11th 13th century frequent clashes easily ancient bridge according theory water begun wash away ancient foundations time bridge appears records explicitly referred use probably repaired taken control bridge village meantime extant arches roman fabric assumed date period bridge apparently ferry service established cross river recorded later times site ancient way station fortress erected middle ages tower built roman emerges reservoir low water attempts reopen bridge early modern era proved unsuccessful architect calculated cost reconstruction bridge realising plans construction project went planning stage project 18th century attempts repair bridge failed plan military engineer included complete reconstruction large span arches planning sketch shows time remaining arches limited right bank finding confirmed drawing voyage years later reconstruction sketch produced rodriguez shows profile bridge rising evenly dominated central arches centre river arches flanked arches sides symmetry arches suggests lieu fortification right bank viewed upstream arch roman times basis modern scientific analysis bridge laid civil engineer survey details condition bridge relocation attempt reconstruct bridge close original possible spanish scholar points slight changes main body avoided course difficult undertaking classified historical heritage spanish authorities construction main feature shape arches uncommon ancient bridge building survey roman bridges showed characteristics vast majority semi circular design according bridge sixteen arches including flood openings right approach following spans estimates square meters feet sources vary arches total length structure spanned low water adds clear span arches assumes basis preserved piers average pier thickness distance bridge ramps corresponded river cross section comparison corresponding discharge profiles roman bridges respectively surviving fabric concentrated right bank current strong number pier stumps rose water surface middle river whilst left bank piers remained standing left followed parts bridge moved safe place essentially images right bridge ramp arch shaped flood openings piers remains scarce remains submerged flooding reservoir approach ramp long wide clear spans arches corresponds span rise ratio respectively accurately fitting inclined contact surface clearly proves roman origin arches extraordinary width appear relation span arch respectively contrast surviving bridge arches laid rubble date arches unknown repairs possibly built period equally evidently post classical origin masonry piers lower projects piers height superstructure piers reconstructed tower according illustration rested pier contrast pier preserved original roman character carefully worked second ran ancient piers provide distinct impression original shape roman bridge particular possible reconstruct relatively precisely rise roman arches basis angles inclined stone supports level arch originally described circular sector points span rise ratio arches value supported depict intact roman arch spanning adjoining fourth bay late early 19th century early examples bridge ranks oldest arched bridges world existence demonstrates contrast previously widely believed taught roman bridge builders possessed intimate knowledge flattened arches pier measuring increase slightly middle river distances piers increase fifth ultimate pier carries distinctive nickname bishop table takes advanced position possesses far largest cross section medieval origin served base replacing ancient arches piers strengthened upstream face pointed facing piers consists local granite set parallel courses use mortar iron ties interior ramps filled roman concrete common method applied roman bridges flattened arches lent bridge elongated appearance roadway following horizontal slightly convex line reconstruction measurements recorded measurements left right bank viewed upstream
Alconétar Bridge