The phrase "most tumbledown" refers to something that is in a state of disrepair, dilapidated or run-down. Therefore, some antonyms for this phrase would include words such as well-maintained, sturdy, strong, new, modern, and polished. These words suggest that the opposite of something that is "most tumbledown" is something that is in good condition, structurally sound, and has a fresh appearance. Using antonyms such as these can be helpful when trying to convey a sense of renovation, rejuvenation, or rebuilding. By focusing on the positive counterpart to a "most tumbledown" object, one can emphasize the potential for improvement, restoration, and growth.