BeijingNationalStadium(Bird'sNest/OlympicStadium)TheBeijingNationalStadium,alsoknownasthebird'snestwillbethemaintrackandfieldstadiumforthe2008SummerOlympicsandwillbehosttotheOpeningandClosingceremonies.In2002Governmentofficialsengagedarchitectsworldwideinadesigncompetition.PritzkerPrize-winningarchitectsHerzog&deMeuroncollaboratedwithArupSportandChinaArchitectureDesign&ResearchGrouptowinthecompetition.Thestadiumwillseatasmanyas100,000spectatorsduringtheOlympics,butthiswillbereducedto80,000afterthegames.IthasreplacedtheoriginalintendedvenueoftheGuangdongOlympicStadium.Thestadiumis330metreslongby220metreswide,andis69.2metrestall.The250,000squaremetre(grossfloorarea)stadiumistobebuiltwith36kmofunwrappedsteel,withacombinedweightof45,000tonnes.Thestadiumwillcostupto3.5billionyuan(422,873,850USD/325,395,593EUR).ThegroundwasbrokeninDecember2003,andconstructionstartedinMarch2004,butwashaltedbythehighconstructioncostinAugust2004.Inthenewdesign,theroofofthestadiumhadbeenomittedfromthedesign.Expertssaythatthiswillmakethestadiumsafer,whilstreducingconstructioncosts.TheconstructionoftheOlympicbuildingswillcontinueonceagaininthebeginningof2005.IndepthThestadium'sappearanceisoneofsynergy,withnodistinctionmadebetweenthefacadeandthesuperstructure.Thestructuralelementsmutuallysupporteachotherandconvergeintoagrid-likeformation-almostlikeabird'snestwithitsinterwoventwigs.Thespatialeffectofthestadiumisnovelandradical,yetsimpleandofanalmostarchaicimmediacy,thuscreatingauniquehistoricallandmarkfortheOlympicsof2008.Thestadiumwasconceivedasalargecollectivevessel,whichmakesadistinctiveandunmistakableimpressionbothfromadistanceandwhenseenfromupclose.ItmeetsallthefunctionalandtechnicalrequirementsofanOlympicNationalStadium,butwithoutcommunicatingtheinsistentsamenessoftechnocraticarchitecturedominatedbylargespansanddigitalscreens.Visitorswalkthroughthisformationandenterthespaciousambulatorythatrunsfullcirclearoundthestands.Fromthere,onecansurveythecirculationoftheentireareaincludingthestairsthataccessthethreetiersofthestands.Functioninglikeanarcadeoraconcourse,thelobbyisacoveredurbanspacewithrestaurantsandstoresthatinvitevisitorstostrollaround.Justasbirdsstuffthespacesbetweenthewoventwigsoftheirnestswithasoftfiller,thespacesinthestructureofthestadiumwillbefilledwithinflatedETFEcushions.Originally,ontheroof,thecushionsweretobemountedontheoutsideofthestructuretomaketheroofcompletelyweatherproof,buttheroofhasbeenomittedfromthedesignin2004.Whiletherainwastobecollectedforrainwaterrecuperation,thesunlightwastofilterthroughthetranslucentroof,providingthelawnwithessentialultravioletradiation.Onthefacade,theinflatedcushionswillbemountedontheinsideofthestructurewherenecessary,e.g.toprovidewindprotection.Sinceallofthefacilities--restaurants,suites,shopsandrestrooms--areallself-containedunits,itispossibletodolargelywithoutasolid,enclosedfacade.Thisallowsfornaturalventilationofthestadium,whichisthemostimportantaspectofthestadium'ssustainabledesign.Theslidingroofwasanintegralpartofth