The question is: "Where is Heaven?"
First, what, or "Who" is "the earth" of verse Revelation 16:1?
Revelation 16:1" And I heard a great voice out of the temple saying to the seven angels, Go your ways, and pour out the vials of the wrath of God upon the earth."
"Who" (not "what") is the "earth" that will receive the vials of wrath? We need not guess:
Jeremiah 22:29 "O earth, earth, earth, HEAR the word of the LORD."
"Who" is addressed to "hear the word of the LORD?"
The Earth is US. The Earth is "the flesh man" - the "carnal-minded man". "The earth" in scripture symbolizes (old) Adam and all who are in him. It is WE, who as "the earth", including the sea and the fountains of waters, are those upon whom all these last plagues are poured, before we can enter into the temple of God in heaven.
The "MAN OF SIN" is "US" - our "OLD MAN" that must be destroyed by "THE BRIGHTNESS OF HIS COMING."
Consider what is said here:
Revelation 10:7 "But in the days of the voice of the seventh angel, when he shall begin to sound, the mystery of God should be finished, as he hath declared to his servants the prophets."
"In the days... (not in THE DAY, singular - but "THE DAYS") when he shall begin to sound (not sound.....but BEGIN to sound) the mystery of God should be finished...filling up the wrath of God", makes it abundantly clear that this is all speaking of an ongoing process (IN THE DAYS of the voice of the seventh angel). This "ongoing" process of judgment within "the earth" which is 'US', and it all adds up to the fact that this book cannot be unsealed to be read, heard or kept... till the seven plagues of the seven angels has been fulfilled within our lives - ALL OF US.
Jeremiah 22:29 "O earth, earth, earth, hear the word of the LORD."
Revelation 22:7 Behold, I come quickly: blessed is he that keepeth the sayings of the prophecy of this book.
Revelation 22:8 And I John [and you and me, Lord willing] saw these things, and heard them. And when I had heard and seen, I fell down to worship before the feet of the angel which shewed me these things.
Revelation 22:9 Then saith he unto me, See thou do it not: for I am thy fellowservant, and of thy brethren the prophets [of "the earth" that "hears these things"], and of them which keep the sayings of this book: worship God.
Revelation 22:10 And he saith unto me, Seal not the sayings of the prophecy of this book: for the time is at hand.
Paul gives us the answer to "where" Heaven is:
Colossians 1:27 "To them God has chosen to make known among the Gentiles the glorious riches of THIS MYSTERY, which is CHRIST IN YOU, the hope of glory."
"The time is at hand" that "the mystery of God...Christ IN YOU, the hope of glory...should be finished" in "the earth", within each of us.
That is why this prophecy is called "the revelation of Jesus Christ" (Revelation 1:1). This book is all about the revelation of Jesus Christ within His elect, and that is why we are admonished in the third verse of the first chapter, and the 10th verse of the last chapter, to "keep the things written therein, for the time is at hand".
The "time is ALWAYS at hand!". Not only some time in the future, or to the specific generation Jesus and the Apostles personally addressed - the time is ALWAYS at hand.....at ALL times......for EVERYONE!
"Heaven," is not a geographical location with a physical city called 'New Jerusalem' as its capitol. Heaven, as revealed in scripture, is in the hearts and minds of God's elect saints. "Heaven" was created by God "in the beginning."
God has no beginning so 'heaven' has not always existed. God is not contained by the heavens. Nevertheless He tells us, for our benefit that...
"...The LORD he is God in heaven above..."(Deuteronomy 4:39, and), "Thus saith the LORD, The heaven is my throne..." (Isaiah 66:1).
Remember Jacob's Ladder?
Genesis 28:10 "And Jacob went out from Beersheba, and went toward Haran.
Genesis 28:11 And he lighted upon a certain place, and tarried there all night, because the sun was set; and he took of the stones of that place, and put them for his pillows, and lay down in that place to sleep.
Genesis 28:12 And he dreamed, and behold a ladder set up on the earth, and the top of it reached to heaven: and behold the angels of God ascending and descending on it."
And who does Christ tell us this ladder with angels represents?
John 1:51 "And he saith unto him, Verily, verily, I say unto you, Hereafter ye shall see heaven open, and the angels of God ascending and descending upon the Son of man."
Genesis 28:16 And Jacob awaked out of his sleep, and he said, Surely the LORD is in this place; and I knew it not.
Genesis 28:17 And he was afraid, and said, How dreadful is this place! this is none other but the house of God, and this is the gate of heaven.
And indeed Christ is the only way to the Father.
John 14:6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
John 10:7 "Then said Jesus unto them again, Verily, verily, I say unto you, I am the door of the sheep.
John 10:8 All that ever came before me are thieves and robbers: but the sheep did not hear them.
John 10:9 I am the door: by me if any man enter in, he shall be saved, and shall go in and out, and find pasture."
John 14:20 "At that day ye shall know that I am in my Father, and ye in me, and I in you."
John 14:5 "Thomas saith unto him, Lord, we know not whither thou goest; and how can we know the way?
Joh 14:6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
John 14:7 If ye had known me, ye should have known my Father also [and "be seated with Him in heaven" (Ephesians 2:6 "And hath raised us up together, and made us sit together in heavenly places in Christ Jesus: and from henceforth ye know him, and have seen him").
John 14:8 "Philip saith unto him, Lord, shew us the Father, and it sufficeth us.
John 14:9 Jesus saith unto him, Have I been so long time with you, and yet hast thou not known me, Philip? he that hath seen me hath seen the Father [and is 'seated in heaven.']; and how sayest thou then, Shew us the Father?
John 14:10 Believest thou not that I am in the Father, and the Father in me [In heaven]? the words that I speak unto you I speak not of myself: but the Father that dwelleth in me, he doeth the works.
John 14:11 Believe me that I am in the Father [in heaven], and the Father in me [in heaven]: or else believe me for the very works' sake."
"The natural man" is expecting a "physical heaven" with all of its physical amenities, which "the natural man" maintains are both physical.........yet at the same time, spiritual. As you can see from above, that is not the case. As Jesus said:
John 3:6 "That which is born of the flesh is flesh; and that which is born of the Spirit is spirit."