13.3 miles (21.4 km) was the longest stretch of guided bus-way in the world when it opened in 2011. The only major commercial airport is Norwich Airport, although London Stansted Airport, the fourth busiest passenger airport in the UK, lies just south of Cambridge in north-west Essex. Universities The University of Cambridge, established at the start of the 13th century and in the town of the same name, is East Anglia's best-known institution of higher learning and is among the oldest and most famous universities in the world. Other institutions include the University of East Anglia (in Norwich), University of Essex, Norwich University of the Arts, Anglia Ruskin University (based in Cambridge), University of Suffolk (based in Ipswich) and University Centre Peterborough. Enterprise zones Great Yarmouth and Lowestoft Enterprise Zone, an enterprise zone initiated by New Anglia Local Enterprise Partnership, was announced in 2011 and launched in April 2012. It includes six sites with a total area of , which have attracted a number of energy-related businesses. The sites are Beacon Park and South Denes in Great Yarmouth, Mobbs Way, Riverside Road and South Lowestoft Industrial Estate in Lowestoft and Ellough Business Park in Ellough near Beccles. There is also an enterprise zone in Cambridgeshire, Alconbury Enterprise Campus in Huntingdon. Symbols and culture A shield of three golden crowns, placed two above one, on a blue background has been used as a symbol of East Anglia for centuries. The coat of arms was ascribed by medieval heralds to the Anglo-Saxon Kingdom of East Anglia and the Wuffingas dynasty which ruled it. The arms are effectively identical to the coat of arms of Sweden. The three crowns appear, carved in stone, on the baptismal font (c.1400) in the parish church of Saxmundham, and on the 15th-century porch of Woolpit church, both in Suffolk. They also appear in local heraldry and form part of the arms of the diocese of Ely and the arms of the borough of Bury St Edmunds, where the crowns are shown pierced with arrows to represent the martyrdom of Edmund the Martyr, the last king of East Anglia. Other users of the arms include the former Isle of Ely County Council, the Borough of Colchester and the University of East Anglia. The flag of Cambridgeshire (adopted in 2015) includes the three gold crowns on a blue field. The East Anglian flag as it is known today was