I'm wondering how I can visit Malbork Castle if I'm visiting Gdansk. Wikitravel says that Malbork is 1.5 hours from Gdansk by train, but doesn't say how much the train is and if it's allowed to go inside the castle and how much admission is.
The question is: if I'm in Gdansk, what should be my budget to visit Malbork castle and return to Gdansk? Also, is it possible to go and return in a morning or do I need the whole day?