In New York City sometimes you see along the sidewalk that people have made glass into the the sidewalks, unusually blue glass and what it is is for under the sidewalk is a room in the basement of the building that used to have coal in the room and the light from outside can come through the glass to light up the room so people could see. This was done before there was electricity and electric lights, so they are very old. But it’s actually beautiful and what you made reminds me of it. They really aren’t used anymore and are more still there for nostalgia (thinking about the past, old times). They are called “sidewalk vault lights”.