Materials usually show anomalous behaviors at ultra-low temperatures. Cryogenic concrete withstands prolonged exposure to temperatures as low as −165 °C and endures repeated ultra-low temperature freezing-thawing cycles. However, such cryogenic environments pose significant challenges to the safety and durability of cement concrete. This book presents an exploration to uncover the secrets of micro/nanostructures and properties of cement concrete under cryogenic attack. Across concise chapters, it introduces the fundamental concepts of cryogenic concrete and calcium-silicate-hydrate (C-S-H), followed by an in-depth examination of pore stability, degradation pathways, and molecular-editing strategies for C-S-H. Additionally, it addresses nanomechanical behavior and frost damage from an atomistic perspective, delivering a complete picture of cryogenic concrete.