When Martin introduced the D12-20 in 1964 it was the first 12-string that was part of the standard lineup. (Martin built a handful of 12-strings as custom orders in the previous decades.) When Martin introduced the D12-20, the urban folk revival was still going strong and the 12-string was a big part of the sound of the era, thanks to Pete Seeger's advocacy of the instrument and the popularity of "Walk Right In" by the Rooftop Singers.
This example was built in 1972 and it is in fine structural condition. There are no cracks in the top, back or sides and the finish is in generally fine shape. There is a deep scratch below the pickguard (see photo #13), a scratch on the side at the base of the neck (see photo #26) and some scuffs on the back. (see photo #18)
There are also a number of minor scuffs and dings here and there. At some point in the guitar's history the neck was reset and it was refretted. We didn't do the work but it was well done. The original Kluson tuning machines were replaced at some point with a set of nice open-back gears that work well and weigh a lot less. The original blue plastic case has been replaced with a good wooden hardshell case. This is a fine sounding guitar with a rich, ringing tone. Thanks to the neck reset and refret, it plays very nicely as well.