Naples, March 12 - Traces of gasoline have been uncovered at the site of the Citta' di Scienza (City of Science) that burned down last week in Naples, prosecutors said Tuesday. At least six samples were found in four different locations at the site, which went up in flames late last Monday. The complex was considered one of Naples' cultural gems. It featured a large interactive science museum that attracted around 350,000 visitors each year and it also had facilities for conferences and other educational activities. Only one of the complex's buildings was untouched by the flames. The mayor of Naples, Luigi de Magistris, has openly suspected mafia foul play.