Let's say there are 3 ships are being built at any one time in San Francisco. If the ships were built on ground, wouldn't 3 ships cover an area the size of San Francisco itself? That's why I see floating ship yards. Something just short of orbital dry docks.
The Enterprise isn't that
big, especially the original. Even downtown San Francisco covers many square miles, check out the fan-pic earlier in the thread of the Enterprise in a dry dock, it's accurate. In fact, the comparison in length between the star ship and a modern super carrier is a pretty good one, just under 1000 ft (280-290 m). CVN-65 is actually 1100 feet long. You could put 10
Constellation class ships into just Golden Gate Park quite easily, and almost
fly one clear under G.G. Bridge at low tide.
Now the Galaxy class is a pretty big ship, you could basically fit the CVN-65 into one of it's engine nacelles. Twenty five times the volume of the original.