Agreed. I think this too. It began with a mist, and it was a pleasant mystery until a maze came along. Without a doubt, you entered. This maze could symbolize an important part of your life perhaps involving other people who choose this particular maze in the mist. The old medieval patriarch dude seems like "authority" but said it is ultimately your choice. The only help he offered was "Choose your way." Whatever branch you choose, there would be a painful, life-changing result. It seems at least you chose what you wanted, the black stairway, but you didn't want the unforeseen consequences that would come with it. You don't want the worst of the two paths, but better the path you chose becomes your path instead of the other you had never wanted. 

I can't recall what was I thinking before I fell asleep, but I think the rusty metal gate should be a symbol of something.

@Coen Wonder, that's what I was thinking, but I did like this dream. I hope you figure out what this means to you. :)

:-) I meant

@Gill Tennant, Thanks for your constructive critisim. I really appreciate them:) I will fine tune my stories when I have the chance.