Walking across the historic Long Biên Bridge is not for the faint of heart. As motorbikes blaze by and trains rumble past, pedestrians have to step along crumbling concrete slabs, with the Red River visible through the gaps, dozens of meters below.
Most cities have train tracks which cut through them; it's nothing too special. But there aren't many cities in which the tracks are basically just another street, with houses and businesses lined up right along the side. Hanoi doesn't have time for your conventions or common sense! If there's a place in the old town where someone can live and work, someone will be living and working there.