1. The largest of several intact sections of the Roman aqueduct serving Nemausus (Nîmes) may be seen at Pont du Gard, 18 km NE of Nîmes. The famous three-tiered aqueduct- bridge spans 275 meters over the Gardon valley. It was built of limestone blocks weighing up to six tons each, fitted together without mortar and secured with iron clamps. This monumental Roman engineering feat, begun by Agrippa in about 19 BC, was completed over a century later during Trajan's reign (AD 98-117). The aqueduct brought water 50 km from the springs of Fontaine d'Eure at Uzès to Nîmes down a total gradiant of only 17 meters, to supply some 400 liters per person per day to town residents.The aqueduct Pont du Gard

3. Cantilevered truss--Firth of Forth rail bridge

4. Beam --Lake Ponchartrain

5. Suspension--Golden Gate

7. Suspension, truss, arched Menai strait, Wales

8. Pont Vecchio, Florence (1342)

9. Cast iron bridge, Coalbrookdale, (1779)

10. Hollow, box girder Germany

11. Tower Bridge, London

12. Maillart designed Salginatobel bridge (1930)

13. New River gorge--largest single arched span (1978)