ancient roman crosses southern france located near town bridge kilometre system built century carry water spring roman colony uneven terrain points underground followed long winding route called bridge gorge highest elevated roman best preserved added list historical importance bridge tiers arches standing high descends height entire length bridge descends mere centimetres gradient indicative great precision roman engineers able achieve simple technology carried estimated imp gal water day homes citizens continued possibly 6th century parts significantly longer lack maintenance 4th century meant increasingly mineral deposits debris eventually flow water collapse fall remained largely intact importance secondary function toll bridge centuries local lords bishops responsible exchange right levy tolls travellers cross river stones looted damage inflicted 17th century attracted increasing attention starting 18th century important tourist destination underwent series renovations 18th 21st centuries commissioned local authorities french state culminated opening new visitor centre removal traffic buildings bridge area immediately today france popular tourist attractions attracted attention succession literary artistic visitors description route location somewhat came providing water supply plains lie city south east sources water low altitude able flow city hills west water supply route difficult engineering point view real alternative look north particular area natural springs built channel water springs near basin distributed private homes city straight line distance takes winding route measuring necessary southernmost foothills known difficult cross covered dense vegetation deep valleys impractical romans attempt tunnel hills required tunnel kilometres depending starting point roughly shaped course eastern end practical way transporting water spring city sea level higher basin provided sufficient gradient sustain steady flow water inhabitants roman city average gradient varies widely course little sections descends gradient average gradient start end far shallower usual roman tenth average gradient rome reason route uniform gradient meant high given limitations technology time varying gradient route engineers able lower height bridge metres metres river exceptionally high roman standards acceptable limits height limit governed profile entire came price creating middle gradient profile relatively steep descending metres kilometre descends metres remaining kilometres section winding route required extraordinary degree accuracy roman engineers allow fall millimetres metres estimated supplied city cubic metres imp gal water day took nearly hours flow source city water arrived open shallow circular basin diameter deep surrounded sort enclosure probably kind small elaborate pavilion excavated traces roof columns decorated fish discovered condition water entered opening metres wide large holes facing wall centimetres wide directed water city main water pipes large drains located floor possibly enable nearby flooded rapidly enable mock naval battles held spring exists site small modern pumping station water pure high dissolved calcium surrounding limestone presented romans significant problems maintaining precipitated water journey caused flow progressively reduced deposits threat posed vegetation penetrating stone lid channel flow water roots introduced algae bacteria process called producing required constant maintenance workers responsible walls clean removing vegetation built underground typical roman constructed digging trench stone channel built enclosed arched roof stone covered earth sections channel solid rock constructed ground remainder carried surface set wall arched bridges substantial remains ground works seen today called stretches hundreds metres stands high surviving parts include arches carrying stream near covers small valley sections tunnel near measuring long far best preserved section entire description bridge built levels high river low water long width varies levels arches main piers line span arches varies slightly constructed independently provide flexibility protect level differing number arches level road bridge added 18th century water high wide carried level upper levels bridge slightly curved upstream direction long believed engineers designed way deliberately strengthen bridge structure flow water like dam wall survey carried showed bend caused stone expanding contracting day heat sun centuries process produced current constructed largely use mortar contains estimated tons limestone volume individual blocks weigh tons stone extracted local quarry located approximately metres downstream banks coarse soft reddish limestone known locally dimension stone production blocks precisely cut fit perfectly friction eliminating need mortar builders left inscriptions stonework conveying messages instructions blocks numbered inscribed required locations right left guide builders method construction fairly understood historians patron rich individual city hired large team contractors skilled labourers surveyor planned route sighting set measuring poles roman feet long figures recorded wax later written builders guide tasks required high degree precision carving blocks water constructed builders extensive use cranes block tackle lift stones place work simple operated largest blocks massive human powered machines late start 20th century complex erected support bridge built large blocks left protruding bridge support frames construction expensive undertaking estimated cost million equivalent years pay new recruits roman legion exterior rough relatively unfinished builders took care ensure interior water smooth possible flow water walls constructed dressed masonry floor concrete covered incorporating minute pottery tile painted olive oil covered mixture lime pork juice produced surface smooth renowned appearance design optimal technique arches clumsy inefficient expensive materials requires later sophisticated design making greater use concrete reduce volume cost construction bridge roughly similar length use far fewer arches roman architects eventually able away altogether los spain bridge near algeria tall slender piers constructed concrete faced masonry brick history construction long credited son law aide marcus year time serving senior magistrate responsible managing water supply rome colonies writing linked construction visit year newer excavations suggest construction taken place tunnels dating time bypassed builders coins discovered outflow older reign emperor basis team led argued completed middle 1st century believed taken years build employing workers 4th century onwards maintenance neglected successive waves invaders disrupted region debris plant roots greatly reducing flow water resulting deposits consisting layers dirt organic material thick wall analysis deposits originally suggested continued supply water late 9th century recent investigations suggest gone use sixth century parts continued significantly longer stones plundered use remained largely intact survival use toll bridge valley 13th century french king granted right levy tolls bridge right later passed bishops return responsible maintaining bridge good repair suffered damage duke use bridge transport artillery wars french led space artillery cross bridge duke second row arches cut away depth original thickness left gap lowest deck wide accommodate cannons severely weakened bridge process local authorities renovated repair cracks fill replace stones lost previous century new bridge built engineer arches lower level road traffic cross purpose built bridge novelist strongly critical construction new bridge commenting reserved eighteenth century monument fifth destroy continued deteriorate time saw risk collapse erosion loss stonework great admiration things roman visited took close interest approved plans architect repair bridge project carried funding provided work involved substantial renovations included replacing eroded stone piers concrete aid stability improving drainage separating bridge stairs installed end walls repaired allowing visitors walk reasonable safety number subsequent projects consolidate piers arches survived floods century lower tier submerged giant flood washed away bridges major flood affected area flood struck badly damaging nearby installations added list criteria human creative genius testimony cultural tradition significance human history description list states hydraulic engineers architects conceived bridge created technical artistic masterpiece tourism tourist attraction centuries outstanding quality bridge masonry led stop french traditional tour country tour france left names stonework 18th century onwards particularly construction new road bridge famous staging post travellers grand tour increasingly renowned object historical importance french national pride bridge long association french monarchs seeking associate symbol roman imperial power king france visited france greeted grand entertainment laid young girls dressed came cave riverside near presented king preserved fruits century later court visited visit january shortly signature treaty great great great grandson commissioned artist produce set paintings roman ruins southern france hang king new dining room palace including picture depicting landscape commission meant ties french monarchy imperial past napoleon iii mid-19th century consciously identified roman emperor accorded great respect roman patronage bridge restoration 1850s essential survival 1990s hugely popular tourist attraction traffic vehicles allowed drive road bridge illegally built structures tourist shops lining river banks architect appetite gain transformed attraction began major year project improve area sponsored french government conjunction local sources entire area bridge new visitor centre built north bank design redevelopment ensured area removal vehicle traffic new museum provides improved historical context visitors today france tourist attractions million visitors reported literary visitors tourist destination writers visited written experience overwhelmed visited told fail work romans seen expected monument worthy hands constructed time object surpassed expectation time life romans produced effect sight simple noble work struck middle wilderness silence render object striking admiration lively called bridge asks oneself force transported enormous stones far quarry brought arms thousands men place live storeys superb respect kept daring echo footsteps immense imagine heard strong voices built felt lost like insect making small felt raised soul said born roman novelist visiting similarly impressed described imposing roman commented monumental thing leave time stand simply feel noble perfect quality greatness vague twilight began gather lonely valley fill shadow roman mighty empire erect supports open solitary tourist sitting sentimental believe people great measured measure greatness individual push gave undertook deepest impressions left speaks manner satisfied mid-19th century writer wrote book les seeing struck dumb walking desert reminds man cultivation disappeared blocks rock clusters rushes oaks stream flows melancholy strand wild mountains silence like midst landscape springs magnificent object civilization created glory fine arts wrote sees thing said comes true isolation dignity weight awful looks built long record beings greater intended stand long dissolution petty race confess great reluctance praise praised man suffering unrest time worse camp days fishing bathing shadow
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