And if you beeline Iron Working to get the colossus, then that tile is even more valuable plus the five gold free. Carthage looks like a lot of fun!
The Colossus only works in one city, so you'll probably have it in your capital, not in a newly build city. Still, if you complete Tradition and then start working on Commerce, you can have your newly founded cities grow really quick if they have two or three sea resources near them.