Excerpt from Guitar Music of the 16th Century by Kieth Calmes
The guitar of the sixteenth century, then called the guitarra or guiterre is known today as the Renaissance guitar or the four-course guitar. The instrument is much smaller than the modern instrument and was usually tuned to the same set of intervals as the modern guitar (there is occasionally a scordatura tuning where the fourth course is tuned down a whole step). Note that this is a treble instrument and realize that the notated pitches would not sound an octave lower as they do on our contemporary guitar. Though pitches were approximated at this time, a popular treatise of the period places the pitches of the guitar a perfect twelfth higher than where they are currently. The fourth course (pair of strings) of the instrument usually consisted of a pair of octaves.