This is what Rome's Jews built as soon as they were allowed to build in the open. From 1555 the community was shut into a few lanes beside the river, and it stayed there for three centuries. When the enclosure was abolished the lanes were pulled down, and the synagogue went up on the cleared ground between 1901 and 1904, free-standing and clear above the low roofs behind it. That siting was the point. Coming to it now, you do not enter by the grand front facing the water. The visitor door is round the side on Via Catalana, and the hall itself is seen on a guided visit rather than walked into.
The ornament is drawn from Assyrian and Babylonian sources rather than from anything Roman. The museum beneath holds what the community carried out of the ghetto: silver, embroidered textiles and marble fragments, and the fittings of the five small synagogues that had shared one building there. Jews have lived in Rome without a break for more than two thousand years, longer than in any other city in Europe. A plaque outside records a two-year-old boy killed in an attack on the building in 1982, which is why security at the door is thorough.