In the early 1970s American archeologists sponsored by the US government made an offer to the citizens of Sremska Mitrovica to completely rebuild the town on another location so that the town could be excavated. The town government refused the request immediately, under pressure from the then hard-socialist Yugoslav government.
During work on the new Sremska Mitrovica trade center in 1972, a worker accidentally broke into an old Roman pot, about 2m deep, over the site of an old Sirmium settlement. 33 gold Roman coins enclosed in a leather pouch were found inside a Roman house wall, probably the hidden savings of a wealthy Roman family stashed centuries ago. Of this extraordinary rare find of Sirmium minted coins were four Constantius II era coins, considered the most valuable examples from the late Roman empire of the 4th century AD. The young worker whose shovel brought this significant discovery to light was never rewarded.
The only known unexcavated Roman horse racing arena in the world is in Sirmium. A colossal building about 150m wide and 450m long lays directly under the Sremska Mitrovica town center and just beside the old Sirmium Emperor's Palace (one of just a few Sirmium publicly accessible archeological sights). The presence of the arena has clearly affected the layout of the present town (Sremska Mitrovica is today about 2-4m above ground line of the former Sirmium settlement). Recently announced cultural and archeological projects for preserving and popularising Sirmium sights haven't included any activity dealing with the arena, probably due to its size — the entire present town center might have to be excavated.