Thanks to growing population (we're over 7 billion people and growing fast), living spaces are at a premium. With mega-cities, the question is where will we put all the people who want to live in each city? Micro-Apartments are one answer. Sized at 200-400 square feet per apartment, they're smaller than typical building codes, while allowing more people per building. Designing a livable micro-apartment is an architectural challenge, and draws on the design for living spaces on boats. A well designed micro-apartment has furniture (like beds) that can fold away, and spaces that can serve multiple purposes. High ceilings can give a feeling of more space, and ingenious use of vertical space can implement storage space even in a small apartment.