I visited this place twice in short succession (April 2007 and June 2007). The first time was, when I was visiting my friend Sigrid (who’s living in Heidelberg), the second time was with because of our annual works outing – and this years trip led us to Heidelberg. lol
The first time I’ve visited the Schloß, I got to see the garden of that gigantic castle ruin (which is a really intact “ruin” and really shouldn’t go by that name ;)), the second time I got to the inside of the castle and the “Apotheken Museum” (apothecary museum).
All is totally worth seeing. But what impressed me, personally, most, was the size of this castle, the castle garden (which is ideal to walk around or sit down and relax) and the beautiful view you’ve got from up there (from the castle and the garden): you can see the whole town Heidelberg, the surrounding “mountains” (or rather “hills”) and the river Neckar.