Big Data to Monitor Big Social Events: Analysing the mobile phone signals in the Brescia Smart City

We present the rst experience, carried out in 2013, devoted to the ex-traction of geo-referenced statistical information from mobile phone signalsto monitor big social events in Brescia, a mid-sized city located near Milan(Lombardy, Italy). The statistical analysis is based on the Telecom ItaliaCityLive database, used to dene raster structures and space-time proleswith the R open source language. The obtained results for the two big eventsheld in Brescia in 2013 (the car race \Mille Miglia" and the bicycle race \Girod'Italia") have proved very useful to this municipal administration to planfuture events, and more generally to develop policies for the \smart city".