The size of heaven [aka the New Jerusalem] depends on which version of the Bible you have. We will use the KJV for this journal. It is 12,000 furlongs [1,500 miles] in length, widith, and height. Heaven is shaped like a square [cube] at the base. Heaven is larger than India with nearly 2 million square feet [Rev. 21:17]. The height is at least 1,400 miles [Rev. 21:16]. This height goes well beyond the earth's atmosphere and into space.
If a building in the city is this high and has a generous 12' story, the building would be over 600,000 stories. If you compare heaven to our moon on size, you would have to be 160,427 miles away. Bible doesn't say heaven is a cube or pyramid.
There's a wall around the city of New Jerusalem that is about 200 miles thick or high/ The NIV says it a cube. There are no mansions. Mansions translated mean 'dorm.' We will live in dorms. The walls are used to keep evil from trying to enter heaven or it could mean those who are evil trying to enter.