Heaven is not limited by the normal boundaries of time and space. Scripture clearly teaches that heaven is a real place that can be seen and touched and inhabited by beings with material bodies. We affirm that truth unequivocally.
But Scripture also reveals heaven as a realm not confined to an area delimited by height, width, and breadth. Heaven seems to span all those dimensions-and more. In Christ's message to the Philadelphian church, for example, He speaks of the eternal realm as "New Jerusalem, which comes down out of heaven from My God" (Rev. 3:12). In the closing chapters of Scripture, the apostle John speaks of "the great city, the holy Jerusalem, descending out of heaven from God" (Rev. 21:10).
The New Heaven and New Earth are seen blending together in a great kingdom that incorporates both realms. The paradise of eternity is thus revealed as a magnificent kingdom where both heaven and earth unite in a glory that surpasses the limits of the human imagination and the boundaries of earthly dimensions.
So heaven is not confined to one locality marked off by boundaries that can be seen or measured. It transcends the confines of time/space dimensions. Perhaps that is part of what Scripture means when it states that God inhabits eternity (Isa. 57:15). His dwelling place--heaven--is not subject to the normal limitations of finite dimensions.
We don't need to speculate about how this can be; it is sufficient to note that this is how Scripture describes heaven. It is a real place where people with physical bodies will dwell in God's presence for all eternity; and it is also a realm that surpasses our finite concept of what a "place" is.
For more information on heaven, take a look at John's book, The Glory of Heaven.