Either you believe Irenaeus' source (undoubtedly Polycarp) that Christianity began in an undetermined place in Antioch (the Antiochenes identify a cave as the place!) OR you accept the Alexandrian tradition that it happened in a building built by a rock near the sea on the eastern shore of Chatby.
I chose the latter option. BOTH are stupid sounding options but the cave in Antioch is utterly ludicrous. Alexandria wins by default.
There are no other options