Years ago a friend had one that I drooled over every time I saw her wear it. It was a VERY long piece of cream and gray splattered wool, cut in front up to the neck line. The neck was cut to the rounded neck line and the back continued on to the ankles as a single piece. It had one single 2 inch piece of self belting to catch the back to the front right under each of the arms, but otherwise swung free and hung nicely because of its weight. It was as classy as my friend was, and I think this lovely creation came from Mexico.
I've often intended to make one like it but haven't found the fabrics perfect for it. Should be heavier than suiting, thick and soft, and not needing hems.