The theorbo is a lute with a second, very long neck. The second set of strings permit it to play low notes. That requires a lot of space, thus making the instrument 6 feet long. Italian musicians built this extraordinary instrument in the 16th Century to accompany operas.
In this video, professional lutist Elizabeth Kenny teaches about the theorbo and performs a variety of Baroque pieces on it. She also describes the challenges of travel with it on the London Underground.
-via Messy Nessy Chic