Due to industrialization in the 18th century, new building types developed such as factories, railway bridges and stations, and market halls. Engineers solved the new building challenges of industry, transportation, and large cities. These structures featured principles of objectivity, functionality, and economical construction, made possible by new techniques like cast iron, wrought iron, steel, and concrete. Notable early engineers included Abraham Darby, Thomas Telford, Isambard Kingdom Brunel, and John Roebling. Their works included bridges, dockyards, and suspension bridges pioneering the use of new materials in structural engineering.