There must be billions of them in the world. We pass them every day. We walk on them. We do not take any notice of them. They are heavy, and usually made of cast iron. They come in many different shapes, sizes and patterns. Look, and you will find them everywhere.

What are they? MANHOLE COVERS, that provide access to local service systems such as water, electricity, gas, and telecommunications.

Post photos of any interesting ones you find here.