What is Heaven?

I believe that Heaven is a place. This place is where God's throne is established.

Psalm 103:19
The LORD has established his throne in heaven, and his kingdom rules over all.

This throne is where God rules creation and this rule is called the Kingdom of Heaven. In other words God rules from Heaven (the place) to all of creation. The very word Kingdom implies a King and a King is a ruler.

Revelation 3:21
To him who overcomes, I will give the right to sit with me on my throne, just as I overcame and sat down with my Father on his throne.

Revelation 11:15
The seventh angel sounded his trumpet, and there were loud voices in heaven, which said: "The kingdom of the world has become the kingdom of our Lord and of his Christ, and he will reign for ever and ever."

So Heaven is a place and it's rule is the Kingdom, just as this world is a place and it's rule is a kingdom.

We know that the Kingdom of Heaven can extend beyond Heaven itself.

Matthew 6:10
Thy kingdom come, Thy will be done in earth, as it is in heaven.

Matthew 11:12
From the days of John the Baptist until now, the kingdom of heaven has been forcefully advancing, and forceful men lay hold of it.

But if Heaven is a place, then where is it located?

People tend to think of up when we talk of heaven, yet in our 3 dimensional understanding, up is really out. E.g. up from Australia is a different direction to up in the USA. I tend to think that Heaven is up but in a dimensional sense. Heaven is the highest dimension in which it contains all of creation including the earth and all the lower dimensions. So from Heaven, all of creation can be seen at once in the same way that we can view 2 dimensional space from the 3rd dimension but the 3rd dimension cannot be viewed from the 2nd. Of course such revelation can be seen if God opens a window/portal in Heaven or the Spirit reveals it to us in vision.

Acts 7:55
But Stephen, full of the Holy Spirit, looked up to heaven and saw the glory of God, and Jesus standing at the right hand of God.

Genesis 28:12
He had a dream in which he saw a stairway [ or ladder ] resting on the earth, with its top reaching to heaven, and the angels of God were ascending and descending on it.

The scriptures also talk about the Heavens as opposed to Heaven and in such instances it is referring to the universe/sky/stars. Paul also mentions the term third heaven and it is suppose by some that the first heaven is the sky, the second is the stars/universe and the third is the place where God's throne is.

In reference to the sky, read Genesis 7:11
In the six hundredth year of Noah's life, on the seventeenth day of the second month-on that day all the springs of the great deep burst forth, and the floodgates of the heavens were opened.

In reference to the stars and universe, read Genesis 15:5
He took him outside and said, "Look up at the heavens and count the stars-if indeed you can count them." Then he said to him, "So shall your offspring be."

In reference to Heaven the place read 2 Corinthians 12:2
I know a man in Christ who fourteen years ago was caught up to the third heaven. Whether it was in the body or out of the body I do not know, God knows.