The city of Los Angeles filed a $20 million lawsuit on Thursday against the real estate developer behind a downtown apartment complex destroyed while under construction in a massive arson fire that engulfed an entire city block in December 2014. The civil suit alleged that Geoffrey H. Palmer and his company, G.H. Palmer Associates, failed to take fire-safety precautions that would have curbed the spread of flames that ended up burning down the multimillion-dollar Da Vinci Apartments complex.