▁and ▁Y O ! ▁S ush i . ▁ ▁Princess h ay ▁is ▁also ▁home ▁to ▁Ex eter ' s ▁Under ground ▁Pass ages , ▁a ▁tour ▁in ▁medieval ▁sub ter rane an ▁passage ways ▁that ▁used ▁to ▁transport ▁water ▁under ▁the ▁city ▁centre . ▁D ating ▁back ▁to ▁the ▁ 1 4 th ▁century , ▁today ▁visitors ▁can ▁enjoy ▁a ▁gu ided ▁tour ▁of ▁this ▁fasc in ating ▁att raction ▁that ▁takes ▁you ▁under ne ath ▁the ▁heart ▁of ▁Ex eter . ▁ ▁Mobile ▁device ▁tracking ▁Crit ic ism ▁has ▁been ▁recogn ised ▁by ▁the ▁media ▁about ▁the ▁use ▁of ▁tracking ▁techn ologies ▁employed ▁by ▁the ▁centre ▁to ▁provide ▁near ▁real - time ▁location ▁data ▁of ▁mobile ▁ph ones ▁within ▁the ▁complex . ▁The ▁system ▁was ▁provided ▁by ▁the ▁ret ail ▁metrics ▁firm ▁Path ▁Int elligence ▁in ▁ 2 0 0 8 , ▁and ▁g athers ▁data ▁by ▁intercept ing ▁T MS I ▁be a cons ▁from ▁mobile ▁ph ones . ▁By ▁using ▁this ▁aggregate ▁data , ▁the ▁system ▁creates ▁a ▁site ▁plan ▁displaying ▁the ▁location ▁of ▁switched ▁on ▁mobile ▁ph ones , ▁and ▁their ▁likely ▁users . ▁ ▁Att empt ed ▁bomb ing ▁ ▁On ▁ 2 2 ▁May ▁ 2 0 0 8 , ▁the ▁sho pping ▁centre ▁was ▁tempor arily ▁ev acu ated ▁after ▁an ▁explos ive ▁was ▁det on ated ▁in ▁one ▁of ▁the ▁restaur ants ▁inj uring ▁only ▁the ▁perpet r ator . ▁On ▁ 1 5 ▁October ▁ 2 0 0 8 , ▁Nick y ▁Re