Twenty-One Twenty-One is an imagination of Hong Kong in year 2121 by architectural poet Wyan Yeung. A hundred years later, some inhabitants on Earth might moves to Mars, while some stay. This suffocating living environment forces the residents to purify their secular desire for fancy living spaces to internal dialogues in mind and soul. As “nano-flats” have become a norm, "coffin terrace”, “windowless toilet”, and "windowless kitchen” have become old-fashioned slangs among the elderly. “Nano-flats” thus became part of the torrent of history, being displayed as museum artifact in Twenty-One Twenty-One.