Does anyone know when the summer opening hours begin for Malbork castle? Rick's book says mid April, and we'll be there on the 20th.
Ever tried Google? You can find much more (and more current info) by looking at the attraction website following a Google query ("Malbork Castle" in the query field). I wouldn't rely on any guidebook for total accuracy when it comes to prices and opening times.
By the way, this is a fabulous site to visit. Give yourself plenty of time to tour it.