Beginning in AD 43, the Romans quickly created a national road network. Engineers from the Roman Army, in most cases, surveyed and built them from scratch. Key locations, both strategic and administrative, were connected by the most direct routes possible. Main roads were gravel or paved, had bridges constructed in stone or wood, and manned waypoints where travellers or military units could stop and rest. The roads' impermeable design permitted travel in all seasons and weather. Following the withdrawal of the Roman legions in 410, the road system soon fell into disrepair. Parts of the network were retained by the Anglo-Saxons, eventually becoming integral routes in Anglo-Saxon Britain, but large sections were abandoned and lost.