The wall … had twelve foundations: these are “foundation stones” (Good News Translation). The picture seems to be that of large stones, each one of which reaches from one gate to the next, twelve in all; or else there is a foundation stone under each of the twelve gateways. In any case, the foundation stones are partly above ground, since the name of the twelve apostles of Christ can be seen written on them. The phrase the twelve apostles of the Lamb presumably refers to the twelve disciples of Jesus, as listed in the Gospels. For apostles see 18.20. It should be clear in translation (which it is not in Revised Standard Version or Good News Translation) that there is one name per stone. New Jerusalem Bible makes this quite explicit: “each one of which bore the name of one of the apostles of the Lamb.” “Foundation stones” in some languages will be expressed as “root stones” or “basic stones.”

Alternative translation models for this verse are:

• They had built the wall (or, fence) of the city on top of twelve large stones. The name of one of the twelve apostles of the Lamb was written on each stone.

Or:

• … Each stone had the name of one of the twelve chief messengers of the Lamb written on it.

Quoted with permission from Bratcher, Robert G. and Hatton, Howard A. A Handbook on The Revelation to John. (UBS Handbook Series). New York: UBS, 1993. For this and other handbooks for translators see here .