Field trips to the Smithsonian are highly recommended by Luna Tractor! The lunar lander LM-2 is stored in the Washington DC Air and Space Museum.
We’ve already referred to the Lunar landing Module (LM in NASA parlance) as the greatest machine ever built. The chance to see a replica in Washington DC was very exciting.
So imagine my amazement to discover that the machine is NOT a replica. It is LM-2, the module they built as a spare unit in anticipation of something going wrong with one of the others. As it happened, things went smoothly (if you don’t count Apollo 13) and it stayed in the shed at Cape Canaveral.
The lesson that the Lunar Module teaches us is fitness for purpose – an old definition of 
quality that has stood the test of time. Take a close look at the panels on the module – it is riveted together with the bare minimum of materials to keep it light.
“Why isn’t it shaped like a plane” asked my traveling agile assistant, whom we shall call ‘Retro-Boy’. The answer lies in the fact that aerodynamics are somewhat irrelevant in a vacuum.
The modular design of these craft allowed the lessons of the previous Apollo mission to be incorporated quickly into the next mission.