According to Official Guinness Records,
A neck tie measuring 808 m (2,650 ft) was made by members of the Academia Cravatica organisation. It took five days to complete and was tied around the arena in Pula, Croatia on 18 October 2003. Widest part - 25m.
Narrowest part - 8m.
For a complete list of 2003 records, please visit 2003 Guinness Records in Croatia.