The NPS does a superb job of accomplishing modernization without destroying the fabric of sites. I particularly like how GB has been updated to appearances of July 1863, permitting us the view that the North & South experienced during the battle. Of course, I do have to add that I much preferred the original visitor center (the Rosensteel building) over the new center (out of scale/large to the surroundings).
Devil's Den was desperately in need of sidewalks and steps repairs, along with updated/increased parking.