This chapter explores the critical aspects of designing and maintaining stable underground openings in mining operations, focusing on both massive and bedded rock formations. It emphasizes the engineering principles essential for ensuring safety, optimizing mining efficiency, and maximizing resource recovery. Key topics include stress distribution analysis, physical properties of rocks, and the application of safety factors in design. Challenges such as inadequate theoretical frameworks and the variability of rock properties are addressed, alongside advancements in experimental methods and computational modeling. Practical applications extend beyond mining to include infrastructure projects and military applications, highlighting the versatility of the design principles discussed. The chapter also examines the influence of time-dependent rock behavior on stability and outlines approaches to mitigate risks associated with stress concentration and structural integrity in underground environments.