  The Death and Life of Great American Cities was written in 1961 and is now
one of the most influential book in city planning. In it, Jane Jacobs proposed
four conditions that promote life in a city. However, these conditions have not
been empirically tested until recently. This is mainly because it is hard to
collect data about "city life". The city of Seoul recently collected pedestrian
activity through surveys at an unprecedented scale, with an effort spanning
more than a decade, allowing researchers to conduct the first study
successfully testing Jacobs's conditions. In this paper, we identify a valuable
alternative to the lengthy and costly collection of activity survey data:
mobile phone data. We extract human activity from such data, collect land use
and socio-demographic information from the Italian Census and Open Street Map,
and test the four conditions in six Italian cities. Although these cities are
very different from the places for which Jacobs's conditions were spelled out
(i.e., great American cities) and from the places in which they were recently
tested (i.e., the Asian city of Seoul), we find those conditions to be indeed
associated with urban life in Italy as well. Our methodology promises to have a
great impact on urban studies, not least because, if replicated, it will make
it possible to test Jacobs's theories at scale.
