The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia and patella forming the knee joint. By most measures the femur is the strongest bone in the body. The femur is also the longest bone in the body.
Marco Polo (1254-1324) was an Italian voyager and merchant who was one of the first Europeans to travel across Asia through China, visiting the Kublai Khan in Beijing. He left in 1271 (he was a teenager at the time) with his father (Nicolo Polo) and uncle (Maffeo Polo); they spent about 24 years traveling.