With rapid urbanization and worsening climate instability, the architectural field urgently needs to rethink traditional housing models. This thesis proposes a shift in how we view urban space, exploring the potential of building underground to address both space shortages and climate pressures. Instead of treating subterranean spaces as mere structural basements for utilities, this research investigates how to design underground environments that are bright, comfortable, and energy autonomous. The core of this work connects traditional climate-responsive architecture with modern engineering. Specifically, it looks at how the massive thermal stability found in historical Persian Sardabs and Shovadans can be combined with modern Finnish rock-engineering techniques and Ground Source Heat Pumps (GSHP).