Look at Betio(Tarawa) on Google Maps-the island is full of buildings. Very few fortifications exist as a rememberance to what happened there in November, 1943.
Sugar Loaf Hill in Okinawa-I heard the top of it was bulldozed due to interference with flight paths to a nearby military base.
I'm sure there are countless reminders of the World War 2 falling apart, being bulldozed, or being reclaimed by the jungle/landscape.
I guess time just marches on.