I can show how the dragon is Rome.

Revelation 12

3. And there appeared another wonder in heauen, and behold a great red dragon, hauing seuen heads, and ten hornes, and seuen crownes vpon his heads.

The dragon with 7 heads appearing. Heaven by the way being the nations where the Christian faith took root, as those with faith have access to our Lord; it is not referencing 3th heaven.

Revelation 17

9. And here is the mind which hath wisedome. The seuen heads are seuen mountaines, on which the woman sitteth.

10. And the woman which thou sawest, is that great Citie which reigneth ouer the kings of the earth.

We meat the beast with 7 heads again, and learnt that the 7 heads are 7 mountains. Rome is that city known to be sitting on 7 hills. While the harlot woman is that great city: the identity of that great city can be confirmed here:

Revelation 11

8. And their dead bodies shall lie in the street of the great citie, which spiritually is called Sodome and Egypt, where also our Lord was crucified.

The great city is spiritually called Sodome and Egypt, a city and a nation. Rome being that city that is also a nation, ruling over the kings of the earth. Even Trump visited Rome as his first foreign trip when he was made President.