The capital city was the most important place for all forces, such as the Golden City for the Munn Kingdom, Casabianca for the Country of Light, and Drekoen for the Country of Darkness. The city was the most powerful emblem and also the symbol of a territory and organization. Therefore, it was essential for Rhode to build one.
Although he could use the construction system to build a massive fortress like the one in the Land of Atonement, it wasn't cost-effective. He had to spend a lot of gold coins where even the lowest-level city required tens of millions and mid-level cities were in the billions. Of course, there were also buildings that were out of specifications, which not even the gold coins of this entire continent could afford—such as the Death Star or something.
This time, he had no intention of doing so.