Your water meter box is usually round with a cast iron or plastic top, and steel sides. Some meter boxes are rectangular and made of concrete. A few are made of completely of plastic. In residential areas, it is usually located between the sidewalk and the street or in the sidewalk (not to be confused with an irrigation meter box, which is typically green, rectangular plastic).
The water meter box serves two functions: It allows you and the city to easily access the water meter and the shut-off valve, and it serves to protect the water meter.