(Photograph from the Romanian Voice website.)
I think that the Metropolitan Cathedral is overrated. Its fame appears to be based on its size ( it is the largest Orthodox cathedral in Romania) and the fact that it is home to the relics (i.e., the bones) of Saint Paraschiva, parton saint of Moldavia.
Mere size is not a criterion of greatness. Don't misunderstand me: the church is pretty enough, but I find it hard to believe that people are impressed, even marginally, by any beauty they see in it. Size is what seems to impress. It is not an unusually beautiful church or an unusually graceful one. Nor an especially awe-inspiring one (I found several very small ones to be in numerous other places throughout the country).
A more plausible explanation for its fame is that it houses the holy relics. To acquire these for the church, Vasile Lupu spent the equivalent of an entire year's national budget in 1641. (Don't let that mislead you; the cathedral wasn't built until the 1830s.) As the patron saint of Moldavia, her remains are preserved in an absolutely stunning--both literally and figuratively--silver reliquary. You will almost certainly find a line of pilgrims or faithful waiting for a moment to pay their respects. The relics alone would be enough to ensure great significance for any location, and they are also the subject of an annual festival. But one is hard pressed to understand why their presence would make the church itself any more noteworthy.