There is an ancient invention. Still used in some parts..

There is an ancient invention. Still used in some parts of the world today. That allows people to see through walls. What is it?

Answer: windows

Windows are openings in walls that are typically made of glass or other transparent materials, and they allow people inside a building to see outside or vice versa. While windows may not be considered a high-tech invention, they have been in use for centuries and continue to be used worldwide for their practicality in providing natural light, ventilation, and a view through walls.