Undeniably one of the most iconic American guitars of all time, the Martin D-18 has been a studio and touring workhorse for countless musicians. It's a staple of bluegrass flatpickers, folk strummers, country players, pop songwriters and everything in between. Vintage specimens, particularly pre-1970s, are extremely collectible, while more modern specimens remain excellent players and investments. Once you play one, you'll understand why the Martin D-18 has become a go-to for so many.