That's how the traditional rooftops of the Bulgarian houses used to be in the past. In many villages, people used stone plates to cover their roofs.
the stones are very durable, compared to the new ceramic tiles, and although some of the houses are hundreds of years old, their roofs still are steady and the water is carried away in a very good way. This proves of course the craftsmanship of the Bulgarian builders. They were people definitely knowing how to make things last for decades and even centuries (apparently proved)!
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