'Gates' in the Bible

I died; but I am now alive until the Ages of the Ages, and I have the keys of the gates of Death and of Hades!

And had a wall great and high, and had twelve gates, and at the gates twelve angels, and names written thereon, which are the names of the twelve tribes of the children of Israel:

On the east three gates; on the north three gates; on the south three gates; and on the west three gates.

And he that talked with me had a golden reed to measure the city, and the gates thereof, and the wall thereof.

And the twelve gates were twelve pearls; every several gate was of one pearl: and the street of the city was pure gold, as it were transparent glass.

And the gates of it shall not be shut at all by day: for there shall be no night there.

Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city.