Psalm 24:7-10 says this:
7 Lift up your heads, O you gates; and be lifted up, you age-abiding doors, that the King of glory may come in.
8 Who is the King of glory? The Lord strong and mighty, the Lord mighty in battle.
9 Lift up your heads, O you gates; yes, lift them up, you age-abiding doors, that the King of glory may come in.
10 Who is [He then] this King of glory? The Lord of hosts, He is the King of glory. Selah [pause, and think of that]!
Why would this say "be lifted up", instead of "be opened"? The commentaries I have read all have their own ideas, but I have a different one! Below is a picture of the Eastern Gates of the Old City of Jerusalem:
These gates were sealed by the Muslims to try and keep Messiah out of the city when He returns. The "secret thing" is that these are NOT the original gates from Bible times! Those gates are underground, below these sealed gates! When Jesus returns and sets His feet on the Mount of Olives, THOSE gates will be "lifted up" and the King of Glory will walk through! HALLELUJAH! Come quickly Lord Jesus!
Shalom in Him!