There are two technologies of wind turbines. One is the horizontal-axis wind turbine (HAWT), which dominates the market of wind farms since the HAWT has a higher energy transfer efficiency. Another is the vertical-axis wind turbine (VAWT), which has unique characteristics to be able to compete with the HAWT, especially in application locations. This paper first introduces the working mechanism of the VAWT and presents different types of VAWTs. Then the paper lists the major difference between VAWTs and HAVTs. It is attractive that the VAWT doesn’t need long length blades and a giant tower so that the VAWT doesn’t require a large open area and can be applied in the areas of metropolitan, community, and resident. In these areas, VAWTs not only can efficiently utilize wind energy but also may have cosmetic effects for the buildings and surroundings. The paper reveals the unique characteristics of the VAWT: replaceable and stackable. The replaceable feature allows an existing VAWT to be altered to a different VAWT type amazingly and the stackable feature lets the VAWT be upgraded conveniently to meet the load requirements. In the paper, the author presents a novel design of the stackable VAWT, a green power tower (GPT).