Instruments similar to what we know as the guitar have been popular for at least 5,000 years. The guitar appears to be derived from earlier instruments known in ancient central Asia as the cithara. During the Middle Ages, guitars with three, four, and five strings existed. The Guitarra Latina had curved sides and is thought to have come to Spain from elsewhere in Europe. Italy was the center of guitar world during the 17th century, and the Spanish school of guitar making only began to flourish late in the 18th century.
Source: Wikipedia.org
Romuald Bárány with one of his guitars.