in the recent Star Wars: The Old Republic expansion Knights of the Fallen Empire, the planet of Zakuul, seat of the Eternal Empire, has a number of buildings that are so big that they're clearly visible from outer space as long pins on the globe, even when so far away that one can see the entire planet at once. Below is a picture of Zakuul with the towers clearly visible.
Here is another image of the towers with a spaceship for comparison. The tower you see here is the same as the tallest tower in the top image. if you zoom in on the orb, you can JUUUST about make out the Eternal Throne itself.
Obviously, on our current Earth with our current tech, such towers would be impossible. However, this is Star Wars. How would the inhabitants of the Galaxy Far Far Away build a tower like this?