Can I build more buildings on the same square?

If you build something in a space that's already occupied, you'll replace the existing building with the new one.

Keep in mind some buildings cannot be removed or "upgraded"... you'll see that as you take over enemy worlds.

Also, use it to your advantage. As you get more and more worlds, you can really start to specialize your planets.

After I get anti-espionage, a like to upgrade one of my happy buildings with the anti-spy center. It gives a decent 20% morale boost and eliminates the need to make spies... unless you want to use them offensively.

T

View a Tile as a piece of Real Estate in real life - as long as you own the land, you can do more or less what you want with it.

If the land is "vacant", you can build what you like subject to the local planning Rules.

If there is a house there and you want a block of flats, the house is "demolished" and replaced, subject to the local planning rules.

In GalCiv, the same applies, subject to "the rules of the game".

Regards
Zy

Using it to your advantage includes the following behaviour:

You can't queue up another unique building. However, if the planet you conquered already has it built, you can keep it. More, if the planet you conquered just has the building in its 'to build' list, you can still build it!

That means by carefully choosing target planets for invasion (using tactics like information warfare that have minimal collateral damage) and having some luck with others, you can have multiple tech or manufacturing capitals in your empire!