A 'return to the Moon to stay' is currently discussed and may lead to the establishment of an initial lunar base during the next two decades. Detailed proposals for a lunar installation are desirable because they put some substance in such advanced planning. For this reason the rationale, base concepts, performance, schedules and cost are the subjects addressed. This documentation ilIustrates the road from a parametric analysis to a conceptual design of an initial lunar base. The approach taken is a detailed analysis of one representative lunarbase concept that could be used as a baseline for further discussion and analysis.ArchitecturaI design concept The main idea of the lunar base design concept consists in the double use of space vehicles employed. The payload shroud of the launch vehicle serves first to protect the vehicle during his ascent through the earth atmosphere, but also as the outer shell of the standard lunar housing module. The dimensions of single modules that can be transported to the lunar surface are 15 m at the base and 21 m in height and have a mass of 50 tons, The principle of a standard module integrates the idea of providing safety in the lunar environment and efficient manufacturing of the hardware involved. Space for living is provided at the lower floor levels for optimum protection of the crew. Technical functions are located more on the upper floors.