Walking around a city (particularly one with a lot of older buildings), you might notice window grills that curve at the bottom. Here's why that curve exists.

While window grills are a common fixture for homeowners looking for added security, some have a "potbelly" feature. Why do window grills curve at the bottom?

They make your house look good and protect it, too. 19. Block-shaped grill with patterned glass window A block-shaped grill ...