The Traditional Sacred Triduum in Rome

The Priestly Fraternity of St Peter will be celebrating the Sacred Triduum this Holy Week in the Church of "Santissima Trinità dei Monti". One of the Fraternity's websites gives the schedule here. There has been much comment on the web about this as Santissima Trinità dei Monti is one of the principal Roman churches, quite a change from the little round-the-corner-and-down-an-alley location of the Fraternity's usual church, San Gregorio dei Muratori, "one of Rome's most obscure and unknown treasures". Santissima Trinità dei Monti, on the other hand, is this beautiful landmark at the top of the Spanish steps. And this means. . .what? I don't know. But as one of the commentators said "It must mean SOMETHING!"