The work for which Brunel is probably best remembered is his construction of a network of tunnels, bridges and viaducts for the Great Western Railway. In 1833, he was appointed their chief engineer and work began on the line that linked London to Bristol. Impressive achievements during its construction included the viaducts at Hanwell and Chippenham, the Maidenhead Bridge, the Box Tunnel and Bristol Temple Meads Station. Brunel is noted for introducing the broad gauge in place of the standard gauge on this line. While working on the line from Swindon to Gloucester and South Wales he devised the combination of tubular, suspension and truss bridge to cross the Wye at Chepstow. This design was further improved in his famous bridge over the Tamar at Saltash near Plymouth.
In 1799, Marc Brunel came to England. He and Sophie were married. Their son Isambard Kingdom Brunel was born in Portsmouth on 9 April 1806. He had two older sisters, Sophia and Emma.
BBC - History - Isambard Kingdom Brunel