I have had a few experiences with "12" gates. People can think me nuts if they want, but I'll tell what I saw about the heart and the Holy City.
I was meditating and praying one day and I was facing east for some reason. All of a sudden it was as if my heart blossomed and opened; and there were 12 paths of light coming from its center. That was similar to when I was caught up in the spirit one day and saw the Holy City from far off. I'll admit I wanted to go inside but was told I wasn't allowed. What I saw was the "cube" again with 12 pathways of Light, and angels of Light were flying in and out.
I was not up close enough to look at the gates, but my guess is they too are of Light -- thus always open, but still visible.
I also figured out a reason I believe I was given the vision of the Holy City with its 12 pathways. There are other Holy Cities in the spiritual heavens; and eventually each City is supposed to be connected with the others with these pathways. I perceived one day there was a problem with the one over Alexandria in Egypt where St. Mark started a church. It caused me come concern. After a period of praying, I was very pleased one day to see the obstacle had been removed when I was in the spirit and saw angels going up and down -- connecting the Coptic Orthodox Cathedral and the whole city of Alexandria below with the Holy City above it.
The "highway" Isaiah wrote about between Jerusalem and Egypt appears to be there today in fine shape; and eventually it will circle the whole earth. The highway from Jerusalem going east connecting it with Babylon in Assyria may not be, I could not say. (For the record, let me say east and west in this context is more magnetic east and west rather than geographical. Does that help explain the odd orientation of the Temple Mount? It seems obvious that the Temple faced magnetic west more than geographical.)
I can tell about another time when I found out what the "glass" is that the people are standing on. I was in the spirit one day with angelic being, and we were talking about something. When I returned to my body, I couldn't remember any of what he said. My guess is it had been planted in my mind to grow. I do remember what I saw. We were walking on what appeared to be a hard clear surface. It didn't strike me as the least bit unusual at the time although I wondered about it later. Below us, under the "glass" was a huge vine that I could not see the end of; and there were beautiful globes of light of different colors attached to it. The globes moved around, and somehow the branches of the vine never got tangled. I knew what those were when I returned to my body. I had seen the souls of men attached to the Vine. When the "grapes" were mature, they would be harvested -- and united with the Spirit with the soul being made immortal.
I had been standing on the firmament, of course, that separates "lower waters" and "upper waters." I did not realize it was "spiritual gold," however, until I discussed this with someone else who said it sounded as if I had seen spiritual gold. That almost has to be right since we're also told the "streets" are made of gold -- and the gold in the Holy City is transparent. It probably depends on how you look at it. It can look like a sea of glass, completely transparent; but it could also appear azure blue the way oceans and the sky look blue.
Why is earthly gold yellow then? Ah, that's because men crave it and have put so much spiritual energy into it. I've never liked wearing gold. Even in my younger days, it made me feel uncomfortable. My guess is I was picking up on the negative spiritual energy in it.
