Complex sentence: The Main landmark in the village, is a Mill, which is a replica of one that stood on its site before demolishment in 1984, when at the time, a old WW2 bomb was found in the "Old Smithy's" garden.
Split into simpler sentences: The main landmark in the village is a Mill, which is a replica of one that stood on the site before being demolished in 1984. During the demolition an old WW2 bomb was found in the "Old Smithy's" garden.