Complex sentence: Built in 1954, and consisting of approximately 1,500 apartment units, they fell into disrepair and became quite dangerous and by the 1980s only 300 families lived there and the buildings were falling apart.
Split into simpler sentences: Built in 1954, and consisting of approximately 1,500 apartment units, they fell into disrepair and became quite dangerous. By the 1980's, only 300 families lived there and the buildings were falling apart.