In the Old Testament they had "keepers of the gate of the tabernacle" who were "keepers of the entry" (1 Chronicles 9:19-23) that kept the unworthy from entering the Temple.
1 Chr. 9: 17-18, 21-22, 24, 26
17 And the porters were, Shallum, and Akkub, and Talmon, and Ahiman, and their brethren: Shallum was the chief;
18 Who hitherto waited in the king’s gate eastward: they were
porters in the companies of the children of Levi.
• • •
21 And Zechariah the son of Meshelemiah
was porter of the door of the tabernacle of the congregation.
22 All these which were chosen to be
porters in the gates were two hundred and twelve. These were reckoned by their genealogy in their villages, whom David and Samuel the seer did ordain in their set office. ..
24 In four quarters were the
porters, toward the east, west, north, and south…
26 For these Levites, the four chief porters, were in their set office, and were over the chambers and treasuries of the house of God.
The tabernacle also is very similar to the New Jerusalem:
Rev. 21:12 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. 13 There were three gates on the east, three on the north, three on the south and three on the west. 14 The wall of the city had twelve foundations, and on them were the names of the twelve apostles of the Lamb.
The "cube" of the New Jerusalem has MANY more similarities to the Temple than just the number of gates.
Here is an EXCELLENT talk on the correlation between the two:
http://www.youtube.com/watch?v=ZLy2tIbqeAc" onclick="window.open(this.href);return false;