Which is correct?

I will go see the sights.


I will go see the sites.
Both are correct.
In the context of tourism, most people go to see the sights.
In the context of archaeological digs, researchers go to see the sites.

The majestic sight of Grand Canyon is unforgettable. Sight- is a view

This will be the site of the new stadium -Site is a location. Being on site = being on location.

From the sound perspective, they are nearly identical so it will depend on how it is used in a context

from which then the listener can distinguish which one it is.
 CalifJim's reply was promoted to an answer.