It had a great, high wall with twelve gates, and with twelve angels at the gates. On the gates were written the names of the twelve tribes of Israel.
References for Revelation 21:12
There were three gates on the east, three on the north, three on the south and three on the west.
The wall of the city had twelve foundations, and on them were the names of the twelve apostles of the Lamb.
References for Revelation 21:14