Complex sentence: Pope Alexander IV and the Curia continued to live in Naples, until the first week of June of 1255 when they returned to Anagni, and it was not until mid-November that the Pope was back in Rome.
Split into simpler sentences: Pope Alexander IV and the Curia continued to live in Naples, until the first week of June of 1255. They then returned to Anagni, and it was not until mid-November that the Pope was back in Rome.