Q. Why is the famous synagogue in Prague called Alt-Neu, literally “Old-New”?
A. This is the oldest synagogue still standing in Europe. Built before 1270, it is still in use. The name Altneu (“old-new”) probably originated after some early reconstruction or renovation project. Because of his Prague connections, Herzl probably had this name in mind when he called a novel Altneuland – “Old-New Land”. The name has often been used homiletically to urge congregations to put new life into old synagogues.
One must add that there is a theory that Altneu is a version of the Hebrew al t’nai, “on condition”. According to this view, the synagogue was regarded as so old that it was actually built with stones from the Temple in Jerusalem, which were used al t’nai that when the Messiah arrived the stones would be returned to the Holy Land and re-erected as part of the Third Temple.