Many are located around the Iwamura Historical Museum, which is in the mountains a reasonable walk from Iwamura Station.
You can also take a bus from Iwamura Station, which runs a few times a day.
This area is where the former residence of the lord of the Iwamura domain was located, and the turrets have been restored to create a plaza-like space.
On the mountain behind you, you'll find the remains of Iwamura Castle, one of Japan's three major mountain castles.