They were assembled by hand, without the use of any tools, in the form of a jigsaw puzzle. Cobblestones were usually put in sand, but if the road owner was affluent, they were sometimes set in mortar. Cobblestone roads are usable. They can be cleaned out of trash and debris with little effort. The only real problem with them is that they are not resurfaced often enough to remain smooth. The first recorded use of the word "cobble" was in 1665. It came from the Dutch koppebeek, which means "chips or shavings of stone." In that day and age, a cobbled street would have been made of chipped or shaved stone. As time went on, "cobble" came to mean a small rounded mass of rock, especially one used for paving streets. So, a cobblestone street would be made of many small rocks glued together. Today's roads are made of asphalt or concrete. Both types of roads have their advantages and disadvantages. Asphalt is a soft material that gets hot during sunny days and cold at night. This makes it ideal for warmer climates like California where you need insulation against heat loss and water retention when it rains. Concrete is hard and durable. It does not get hot or cold, which makes it perfect for colder climates like Canada or Europe where temperatures fluctuate greatly throughout the year.