This ugly building in Salerno is the church of S.Trophimena, the protector of Amalfitans. Yes, Amalfitans in Salerno.
The existance of this church, actually closed for the visitors but excavated by archeologists, confirms a story, told by Chronicon Salernitanum, a chronicle written in X century, about the Amalfitans that first have seen their town destroyed by the Longobards of Sicardo, their houses plundered, the body of their protector transported in Benevento, -and than they were transported in Salerno -to repopulate the town maybe.
Later, after the death of Sicardo, the body of the Saint was given back to the Amalfitansand they, after a day when the rests of the Saint were celebrated in Salerno, was embarked on a boat and transportated in the cathedral dedicated to the Saint in Minori. Amalphitans turnd back in their town, too.
So, this church had to exist from the IX century. But it was built on the base of Roman buildings. And later, when the population of this quarter grew, they built a bigger new church using the old church as a crypt.