Dragonstone Skyrim: Where is it?

The Dragonstone Skyrim is sometimes giving you a pain in the ass because it is easy to miss. It is the required item for the first story quest in Whiterun. Actually, the first time I searched for it, I literally missed it and I had to re-explore the dungeon from the front door since I had exited the dungeon and there is no shortcut access. Okay then, full story and description below.Dragonstone