Synagogues may be considered "oldest" based on different criteria. A number of synagogues that predate the expulsion of the Jews from England have been discovered by archaeologists or by historians in buildings that have been in use for other purposes for many centuries. A second set of synagogues post-dates the legal return of Jews to England in the seventeenth century. Some synagogues have been destroyed or demolished and rebuilt on the same site, so that, while the site or congregation may be very old, the building may be modern. Still other old synagogue buildings exist, but were sold by the congregation and are now used for other purposes, some as churches or mosques, others for everything from residences to school recital halls. And some very old synagogues have been in continuous use as synagogues for many centuries.