West Sussex in 1974. In June 1972, British European Airways Flight 548 crashed near Staines just after taking off from Heathrow Airport. This remains the worst air accident in the UK. Historic architecture and monuments Few traces of the ancient British and Roman periods survive in Surrey. There are a number of round barrows and bell barrows in various locations, mostly dating to the Bronze Age. Remains of Iron Age hillforts exist at Holmbury Hill, Hascombe Hill, Anstiebury (near Capel), Dry Hill (near Lingfield), St Ann's Hill (Chertsey) and St George's Hill (Weybridge). Most of these sites were created in the 1st century BC and many were re-occupied during the middle of the 1st century AD. Only fragments of Stane Street and Ermine Street, the Roman roads which crossed the county, remain. Anglo-Saxon elements survive in a number of Surrey churches, notably at Guildford (St Mary), Godalming (St Peter & St Paul), Stoke D'Abernon (St Mary), Thursley, Witley, Compton and Albury (in Old Albury). Numerous medieval churches exist in Surrey, but the county's parish churches are typically relatively small and simple, and experienced particularly widespread destruction and remodelling of their form in the course of Victorian restoration. Important medieval church interiors survive at Chaldon, Lingfield, Stoke D'Abernon, Compton and Dunsfold. Large monastic churches fell into ruin after their institutions were dissolved, although fragments of Waverley Abbey and Newark Priory survive. Southwark Priory, no longer in Surrey has survived, though much altered, and is now Southwark Cathedral. Farnham Castle largely retains its medieval structure, while the keep and fragments of the curtain walls and palace buildings survive at Guildford Castle. Very little non-military secular architecture survives in Surrey from earlier than the 15th century. Wholly or partially surviving houses and barns from that century, with considerable later modifications, include those at Wanborough Manor, Bletchingley, Littleton, East Horsley, Ewhurst, Dockenfield, Lingfield, Limpsfield, Oxted, Crowhurst Place, Haslemere and Old Surrey Hall. Major examples of 16th-century architecture include the grand mid-century country houses of Loseley Park and Sutton Place and the old building of the Royal Grammar School, Guildford, founded in 1509. A considerable number of smaller houses and public houses of the 16th century are also still standing. From the 17th century the number of surviving buildings proliferates further. Abbot's Hospital, founded in 1619, is a grand edifice built in the Tudor style, despite its date. More characteristic examples of major 17th-century building