Great North Way
This is a well signed, official cycle route running along National Cycle route 12 from Potters Bar to Letchworth. The route passes through Hatfield and Welwyn Garden City and includes several traffic free sections. Route highlights include the splendid Knebworth House and Hatfield House (see videos). Both have extensive parkland and gardens to explore and are well worth visiting if you have time. Also of interest are the Mill Green and Letchworth Heritage museums.
The route is easily accessible with train stations at either end.