"The original shape of the guitar in the fourteenth and fifteenth centuries. A plucked string instrument that was first called a guitar appeared in Spain around the turn of the fifteenth century. The instrument was actually called a vihuela, and consisted of four double-strings (paired courses)."
"Antonio de Torres Jurado (13 June 1817 – 19 November 1892) was a Spanish guitarist and luthier, and "the most important Spanish guitar maker of the 19th century."[1]
It is with his designs that the first recognizably modern classical guitars are to be seen.[2] Most acoustic guitars in use today are derivatives of his designs."
First steel string guitar was invented by a German immigrant.
Christian Frederick Martin
"Although steel-stringed acoustic guitars are now used all over the world, the person who is thought to have created the first of these guitars was a German immigrant to the United States named Christian Frederick Martin (1796-1867). Guitars at the time used so-called catgut strings created from the intestines of sheep."