Letchworth is often visited by those interested in town planning and the cloisters is a very unusual building. It isn't normally open to the public but if you are in town its worth a look.
www.thecloisters.org.uk/
Cloisters Rd Letchworth Herts SG6 3TH
+44(0)1462 678059
Google map: bit.ly/pw3MHj
Letchworth Rail Station approx 1mile.