VERIFY: Is Milledgeville really the only city in the US designed to be a capital city?

A post by Georgia's Old Capital Museum at the Depot has been getting a lot of attention on social media. The post says, "Did you know that Milledgeville is the only city in the U.S., with the exception of Washington D.C., actually designed to be a capital city?" So we set out to VERIFY if this is true.
Published: 9:01 AM EDT May 10, 2019
Updated: 9:00 AM EDT May 10, 2019