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1Introduction``Intoday'sDublin,youwouldn'tneedanovelist'somnisciencetofollowLeopoldBloom,StephenDedalus,andBuckMulliganaroundthecity;youcouldjusttracktheircellphoneusage.AndifLeopoldcouldgetaccesstothelogs,hecouldfigureoutpreciselywhatMollywasupto.''Mitchell(2003,page116)Whetheryouareatechno-enthusiastornot,Mitchell's(2003)e-topiahascertainlybecomearealityinthefieldofmobilecommunications.Justlookatdatafromtheboomingmobilecommunicationsindustry.AccordingtotheEuropeanInformationTechnologyObservatory(EITO,2004),cellphonesubscriptionsinWesternEuropereached350millionin2003(157millionintheUSA).InItaly,wherethecasestudiespresentedinthispaperarelocated,thenumberofusersisapproximately54million(EITO,2004)öthatis,thesecondlargestmarketinEuropeafterGermany.Further-more,withatotalpopulationof57million,Italyhasoneofthehighestpenetrationsofmobiledevicesintheworld.Whyshouldtheurbanplanningcommunitybeinterestedintheaforementioneddata?First,thewidespreaddeploymentofmobilecommunications,supportedbypersonalhandheldelectronics,ishavingasignificantimpactonurbanlife.Peoplearechangingtheirsocialandworkinghabitsbecauseofthenewtechnology(Rheingold,2002).Activitiesthatoncerequiredafixedlocationandconnectioncannowbeachievedwithhigherflexibility,whichresultsintheusers'abilitytoactandmovemorefreely[forananalysisinthecorporateworkingdomain,seeDuffy(1997)].Asaconsequence,urbandynamicsarebecomingmorecomplexandrequirenewanalysistechniques.Second,andmoreimportantlyinthiscontext,databasedonthelocationMobileLandscapes:usinglocationdatafromcellphonesforurbananalysisCarloRatti,DennisFrenchmanSENSEableCityLaboratory,MassachusettsInstituteofTechnology,room10-485,77MassachusettsAvenue,Cambridge,MA02139,USA;e-mail:ratti@media.mit.eduRiccardoMariaPulselliDepartmentofChemicalandBiosystemSciences,UniversityofSiena,Italy;e-mail:pulselli@unisi.itSarahWilliamsSpatialInformationDesignLaboratory,1172AmsterdamAvenue,400AveryHall,ColumbiaUniversity,NewYork,NY10027,USAReceived18February2005;inrevisedform20September2005EnvironmentandPlanningB:PlanningandDesign2006,volume33,pages727^748Abstract.Thetechnologyfordeterminingthegeographiclocationofcellphonesandotherhandhelddevicesisbecomingincreasinglyavailable.Itisopeningthewaytoawiderangeofapplications,collectivelyreferredtoaslocation-basedservices(LBS),thatareprimarilyaimedatindividualusers.However,ifdeployedtoretrieveaggregateddataincities,LBScouldbecomeapowerfultoolforurbananalysis.Inthispaperweaimtoreviewandintroducethepotentialofthistechnologytotheurbanplanningcommunity.Inaddition,wepresentthe`MobileLandscapes'project:anapplica-tioninthemetropolitanareaofMilan,Italy,basedonthegeographicalmappingofcellphoneusageatdifferenttimesoftheday.Theresultsenableagraphicrepresentationoftheintensityofurbanactivitiesandtheirevolutionthroughspaceandtime.Finally,anumberoffutureapplicationsarediscussedandtheirpotentialforurbanstudiesandplanningisassessed.DOI:10.1068/b32047ofmobiledevicescouldpotentiallybecomeoneofthemostexcitingnewsourcesofinformationforurbananalysis.Locationaldataarebecomingincreasinglyavailableandtheirapplicationsarecur-rentlyahottopicinthecellphoneindustry(see,forinstance,).Theyaregenerallyreferredtoaslocation-basedservices(LBS)övalue-addedservicesforindividualsintheformofnewutilitiesembeddedintheirpersonaldevices.Examples,bothimplementedandspeculative,includesystemsprovidinginformationaboutone'ssurroundings(neighbouringrestaurants,museums,emergencyshelters,andsoon);dis-tributedchatlinesaimedatallowingpeoplewithsimilarprofilestoencountereachotherinspace,viaakindoftechnologicallyaugmentedserendipity;and`digitaltapestries'thatattachdifferenttypesofinformationtophysicalspaces(seesectionsbelowfordetailedreferences).Andyet,surprisinglyenough,aggregatedlocationaldatahavenotbeenusedtodescribeurbansystems.Researcheffortsintheareaaresparse;thescientificliteraturemostlyignoresthemessuchasthemappingofthecellphoneactivityincitiesorthevisualizationofurbandynamicsonthebasisofhandsetmovement.Howcouldthisbe?Themostreasonableassumptionisthatscholarlyresearchhasbeenhamperedsofarbythedifficultyofaccessingrawdata.Also,inmostcases,meredataisnotenough,andthedevelopmentofadhocsoftwareandsystemsinpartnershipwithcellphonecompaniesisrequired.Inthisstudytheresearchteamhashadtheopportunitytoestablishapartnershipwithaleadingmobilenetworkoperator,thusgainingaprivilegedinsightintohowaggregateddatafrommobiledevicescanrevealurbansystems.ThemetropolitanareaofMilan,Italy,hasbeenselectedastheinitialcasestudy;thiscombinesanumberofinterestingplanningfeatureswithoneofthemostdevelopedmarketsformobilephones.Resultsseemtoopenthewaytoanewapproachtotheunderstandingofurbansystems,whichwehavetermed`MobileLandscapes'.MobileLandscapescouldgivenewanswerstolong-standingquestionsinarchitectureandurbanplanningöhowtomapvehicleoriginsanddestinations?Howtounderstandthepatternsofpedestrianmovement?Howtohighlightcriticalpointsintheurbaninfrastructure?Whatistherelationshipbetweenurbanformsandflows?Andsoon.Thetraditionalapproachestogaininginf