Interlocking pavers are made of either compressed concrete, or clay, and have a minimum strength rating of at least 8,000 psi. Pavers have been used to make roads, driveways, patios, and pedestrian walkway areas for thousands of years, dating back to the early Roman Empire. Today’s pavers are different in style, similar in process. The Romans excavated their roadways and compacted native soils using tree trunks, building up and compacting soils in several lifts until the base for their pavers was sturdy. They used large, square or octagonal shaped granite stones to pave their road ways, many of which are still intact today. The modern installation methodology is similar in nature, using a compacted base material and laying segmental interlocking units to form a flexible, yet unbelievably study surface.