Gardening and Horticulture - Ancient Climbing Rose Monster from HELL!

Hello,
I was looking for advice with a completely unruly gigantic monster of a climbing rose. It went wild and untamed for about 20 years. Some of the canes were almost 2 inches in diameter. It's original trellis was lifted off the ground, and the rose was holding it up. It's main support was provided by a birch tree that it swallowed whole.

I have now cut out the old trellis, and freed the poor birch tree, and now I have the monster laying on the ground. The canes are about 15 feet in length.

Does anyone have some advice to help me get this thing domesticated again? It's going to be a blood-bath.

Cut out older, larger canes. Limit canes to about four or six with an even number on each side to balance the plant. Keep younger, green canes. Tips of canes should be cut back so they fit the size of the new trellis or surface they will cover. Climbing roses tend to produce canes one year and then flower the next year. So, if you cut back severely, you will likely have no blooms until next year. Side growth off the main can be cut back to the second growth bud, leaving about two or three inches. Take care not to damage the canes you are retaining. Once pruned, you should not have to prune for a couple years. Then, prune every 3-4 years to remove older less vigorous canes at base and twiggy canes. You want to save the vigorous canes that are long and flexible and can be trained to grow horizontally. Train canes to grow horizontally so climbers will produce stems along main canes and this will give you more blooms.