Ghost town  The Last Survivor: in search of Martin Zaidenstadt
Timothy W Ryback Picador, 195pp, £14.99  With spring in the air
and summer on its heels, it cannot be long before the return of
that useful conversation oiler: "Where are you going for your
holidays?" Quite an unusual answer, one that might well seize up
a sticky conversation altogether, would be "Dachau". More
seriously, how long does it take for a town where horrible
things have happened to be free from its past? For some time
after 1066, Anglo-Saxons presumably found it painful to visit
Hastings, and the English must have avoided Bannockburn for a
while. But spots of blood do fade, bullet holes can be filled in
and places recover - prosper even, if they are attractive
enough, like Normandy or Waterloo.  But Dachau has not
recovered, although it is certainly picturesque. The 1,200-year-
old town lies in the pleasant hills just north of Munich. Its
half- timbered cottages and cobble-stoned streets lined with oak
trees cluster round a hill topped b