LondonisthecapitalcityofEnglandandtheUnitedKingdom,thelargestmetropolitanareaintheUnitedKingdom,andthelargesturbanzoneintheEuropeanUnionbymostmeasures.LocatedontheRiverThames,Londonhasbeenamajorsettlementfortwomillennia,itshistorygoingbacktoitsfoundingbytheRomans,whocalleditLondinium.London'sancientcore,theCityofLondon,largelyretainsitssquare-milemedievalboundaries.Sinceatleastthe19thcentury,thenameLondonhasalsoreferredtothemetropolisdevelopedaroundthiscore.ThebulkofthisconurbationformstheLondonregionandtheGreaterLondonadministrativearea,governedbytheelectedMayorofLondonandtheLondonAssembly.

　　Londonisaleadingglobalcity,withstrengthsinthearts,commerce,education,entertainment,fashion,finance,healthcare,media,professionalservices,researchanddevelopment,tourismandtransportallcontributingtoitsprominence.Itistheworld'slargestfinancialcentrealongsideNewYorkCityandhasthefifth-largestcityGDPintheworld(andthelargestinEurope).IthasthemostinternationalvisitorsofanycityintheworldandLondonHeathrowistheworld'sbusiestairportbynumberofinternationalpassengers.London's43universitiesformthelargestconcentrationofhighereducationinEurope.In2012LondonwillbecomethefirstcitytohostthemodernSummerOlympicGamesthreetimes.

　　Londonhasadiverserangeofpeoples,culturesandreligionsandmorethan300languagesarespokenwithinitsboundaries.InJuly2010GreaterLondonhadanofficialpopulationof7,825,200,makingitthemostpopulousmunicipalityintheEuropeanUnion.TheGreaterLondonUrbanAreaisthesecond-largestintheEUwithapopulationof8,278,251,whileLondon'smetropolitanareaisthelargestintheEUwithanestimatedtotalpopulationofbetween12millionand14million.Londonhadthelargestpopulationofanycityintheworldfromaround1831to1925.

　　LondoncontainsfourWorldHeritageSites:theTowerofLondon;KewGardens;thesitecomprisingthePalaceofWestminster,WestminsterAbbey,andStMargaret'sChurch;andthehistoricsettlementofGreenwich(inwhichtheRoyalObservatorymarksthePrimeMeridian(0°longitude)andGMT).OtherfamouslandmarksincludeBuckinghamPalace,theLondonEye,PiccadillyCircus,30StMaryAxe("TheGherkin"),StPaul'sCathedral,TowerBridge,TrafalgarSquareandWembleyStadium.Londonishometonumerousmuseums,galleries,libraries,sportingeventsandotherculturalinstitutions,includingtheBritishMuseum,NationalGallery,BritishLibrary,Wimbledonand40theatres.London'sChinatownisthelargestinEurope.TheLondonUndergroundistheoldestundergroundrailwaynetworkintheworldandthesecond-mostextensive(aftertheShanghaiMetro).