A building in wire frame with other wire frame elements (road, sidewalk, plateau) looks busy and unattractive.

A solid fill color, properly placed, would help the eye to infer the map.

But I am unable to find the menu item which allows a selected building or wall to be "solid filled", or "colored".

Can anybody help me to find the menu item and process which allows a "color solid fill" to be applied to the selected part?

Thanks for your assistance!