Throughout the Big Book of Alcoholics Anonymous, Bill W. made a number of construction references which eventually lead to the building of an archway.  The archway to freedom is complete after finishing the fifth step.

The Bedrock: We perceive that only through utter defeat are we able to take our first steps toward liberation and strength. Our admissions of personal powerlessness finally turn out to be firm bedrock upon which happy and purposeful lives may be built. (Twelve & Twelve, 21:3)

The Foundation: It was only a matter of being willing to believe in a Power greater than myself. Nothing more way required of me to make my beginning. I saw that growth could start from that point. Upon a foundation of complete willingness I might build what I saw in my friend. Would I have it? Of course I would! (BB 12:4)

The Cement: The feeling of having shared in a common peril is one element in the powerful cement which binds us. But that in itself would never have held us together as we are now joined.The tremendous fact for every one of us is that we have discovered a common solution. We have a way out on which we can absolutely agree, and upon which we can join in brotherly and harmonious action. This is the great news this book carries to those who suffer from alcoholism. (BB 17:2, 17:3)

The Cornerstone: We needed to ask ourselves but one short question. Do I now believe, or am I even willing to believe, that there is a Power greater than myself?" As soon as a man can say that he does believe, or is willing to believe, we emphatically assure him that he is on his way. It has been repeatedly proven among us that upon this simple cornerstone a wonderfully effective spiritual structure can be built.(BB 47:2)

The Keystone: This is the how and why of it. First of all, we had to quit playing God. It didn’t work. Next, we decided that hereafter in this drama of life, God was going to be our Director. He is the Principal; we are his agents. He is the Father, and we are His children. Most good ideas are simple, and this concept was the keystone of the new and triumphant arch through which we passed to freedom.(BB 62:3)

The Foundation Stone: Helping others is the foundation stone of your recovery. A kindly act once in a while isn't enough. You have to act the Good Samaritan every day, if need be. (BB 97:1)

The Path to Freedom: Taking this book down from our shelf we turn to the page which contains the twelve steps. Carefully reading the first five proposals we ask if we have omitted anything, for we are building an arch through which we shall walk a free man at last. Is our work solid so far? Are the stones properly in place? Have we skimped on the cement put into the foundation? Have we tried to make mortar without sand? (BB 75:3)