How big should a Minecraft building be?

I would like to know how big I should build this tower here. (So for example 64 x 64 blocks)

This is a sketch that is to be adopted by the Art in the game. But how big should I make the whole thing so that everything is nice and symmetrical?

P.s: I play in creative mode and the tower should be adapted to the normal Minecraft figure. So about 1: 1 to real life… ^^

You can build it 20 or 30 blocks high and 60 70 wide

1: 1 = 1 block 1 meter

In any case, the tower should be loosely 80 blocks so that the whole thing can be nicely refined with decorative and creative ideas that make the whole look more realistic.