It is often said that "all roads lead to Rome," and in fact, they once did. The road system of the Ancient Romans was one of the greatest engineering accomplishments of its time, with over 50,000 miles of paved road radiating from the center at the city of Rome. Although the Roman road system was originally built to facilitate the movement of troops throughout the empire, civilians eventually used it for other purposes then and even now. Of course, the roads were used for trade, as were the waterways surrounding and connecting parts of the Roman Empire to itself and the rest of the world. The Romans had exceptional nautical technology for their time ;however their network of roads was unparalleled in convenience and was often the only choice for travel or shipping goods for legions at war. The Romans were the first ancient civilization to build paved roads, which did not prevent travel during or after inclement weather. Indeed, mud or gravel would hinder, if not completely halt many vehicles pulled by animals or other people. This was very for the Romans for the roads were its lifelines. Roman engineers, however, did not stop with just paving Roman roads. Roads were crowned that is, they were higher in the middle than on the sides to allow water to run off and they often had gutters for drainage along the shoulders. Probably the most incredible engineering feat concerning the Roman road system, though, is how well the roads were built. In building a road the field engineer, assisted by a stake man aligned the road with a groma and ran levels with chorobates. A plow was used to loosen the soil and mark the trench fossa margins. Workmen dug trenches for a roadbed with a depth of 6 to 9 feet, carrying away the dirt in baskets. The earthen bed was tamped firm. The foundation of lime mortar or sand was laid to form a level base. Next came stones of about 4 to 5 in. in diameter, cemented together with mortar or clay. This layer could be anywhere from 10 inches to 2 feet deep. The next course was 9 to 12 inches of concrete filled with shards of pottery or stone. Atop this layer was the nucleus, a concrete made of gravel or sand and lime, poured in layers with each layer compacted with a roller. This layer was one foot at the sides and 18 in at the crown of the road. The curvature was to allow good drainage to the finished road. The top course was the summum dorsum, polygonal blocks of stone that were 6 inches or more thick and carefully fitted atop the still moist concrete. When a road bed became overly worn, this top course was removed, the stones turned over and replaced. A road was 9 to 12 feet wide, which allowed 2 chariots to pass in each direction. Sometimes the road was edged with a high stone walkway. Mile markers indicated the distance. A cart, fitted with a hodometer was used to measure distances. A cart that was fitted with a hodometer had a special wheel attach to it, 4 feet in diameter and 12.5 feet in circumference. Four hundred revolutions made a Roman mile. Many are still major thoroughfares for cars today. Indeed, their road-building methods were unsurpassed until the invention of the macadam in the 19th century. These technological advantages made travel and the shipment of goods across land much easier. Romans shipped lots of goods within the vast expanses of their empire as well as to the rest of the world. Goods were constantly being shipped throughout the empire, depending on the location within the Empire, as well as supply and demand. Present-day Great Britain, for example, was a valuable possession to the Romans because of its silver deposits, which were used for jewelry and money. Great Britain also supplied a lot of wool to the rest of the empire. From the southeastern corner of the empire, the Romans imported many dyes for clothing and make-up from the Near East. Over-water transportation usually played a role in imports from the Near East or Africa, from whence they imported Egyptian cotton, or exotic animals for the gladiators to fight. Of course, Rome was connected to the Far East via the Silk Road, the source of silk and other goods imported from Asia. No matter what or from where, if the Romans wanted something exotic, it was probably shipped into Rome. The roman army was one of the benefactors of the roads. Traveling great distances in a short time help fight off unruly barbarians in the north, and menacing armies in the south. Much of the roads built were built by roman soldiers. These labors were specializing in their fields of road building. For roads were important to Roman army, and it was in there best interest to build roads to the best of the abilities.