The review discusses 3D designs of coupled strip lines and their application in microwave devices. It is noted that 3D designs of coupled strip lines have advantages over other strip structures due to the possibility of forming a strong electromagnetic coupling between the strips. This result is achieved by simple technological methods, such as installing a vertical substrate with soldering (or welding) of conductors oriented horizontally and vertically on the substrates, respectively. The article briefly covers the history of development and provides a classification of these structures. The advantages and disadvantages of devices built based on such structures are analyzed. Methods for analyzing them and improving their characteristics are considered. It is emphasized that three-dimensional designs of coupled strip lines represent a promising direction in the development of microwave technologies and can be widely used in various devices.