iron balconies were replaced with concrete ones and later sealed with windows. roofs were often flat with an open terrace and later renovated to allow for additional residential space. wooden windows gave way to stainless steel windows. air conditioning units were added to the windows in the 1970s and 1980s. often clothes racks were added below the windows and hung above the sidewalk or street below. signs were hung on the exterior walls and protruded onto the streets below.