Where is Heaven?
Is that some sort of comic book convention?
Most mythologies (also known as religions) offer something in exchange for following a number of precepts. Most of the organised religions basically try to achieve a certain social order and peace in a society. It is much easier to do so if you promise a price for good behaviour and what is better than eternal life in a paradise, heaven or whatever you choose.
There is no obvious reason to believe in any of the "religions" than there would be to believe in the ancient Greek gods or in the sanctity of cows. There is no obvious reason either to think that there is nothing out there, whatever shape may it take, that has some connection with eternity or our creation. If something is certain, is uncertainty on the fundamental questions of life.
A mistake that many people make is, they live thinking that they don't have any religion. EVERYBODY has religion! People who say that they don't have religion, simply have a religion of no-religion.
The important thing is to find the religion that is correct. Everybody dies, even the no-religion people. What this means is that eternal life is not part of this life.
If anybody wants eternal life, he has to find the right religion. Why? Because EVERYBODY has religion in some form... even if it is simply a religion of no-religion. Find the right religion, and live forever in a new life.