The cities of Greece had their own calendars, so how did they all know when the god Apollo had returned from the northern realms and it was time to consult the oracle at Delphi? The authors show that the heliacal rising of the constellation Delphinus probably provided the annual marker, and that because of the mountains it appeared to rise a month later at Delphi than elsewhere, giving would-be visitors time to travel. The landscape of Delphi was itself instrumental in creating or enhancing the cosmology of Apollo.