This paper initially presents a review of the code of practice progression for retention system design and construction over the past three decades from a personal professional perspective. Progresses in design methodology and analysis tools over each decade will be discussed and the main design and construction challenges will be highlighted. It will highlight the current design approach to retention system for deep excavations and seawalls, and the importance of soil-structure interactions with the advancement of computing power. Some of the technical challenges experienced from various projects will be shown to emphasize the importance of understanding and incorporation of geological features and characteristics of soil and weak rock in the soil-structure interaction analysis. An attempt will be made to forecast what the design methodology will be like in the next decade, with the technological driving forces including AI, digitalization and 3D modelling.