Final answer:
At the same horizontal level as the greater trochanter of the femur is the gluteal tuberosity of the femur, serving as an attachment area for muscles and continuous with the linea aspera.
Step-by-step explanation:
The structure at the same horizontal level as the greater trochanter of the femur is the gluteal tuberosity of the femur, which is on the posterior shaft of the femur and extends inferiorly from the greater trochanter.
The greater trochanter is a prominent landmark on the proximal femur, which serves as the point of attachment for multiple muscles that act across the hip joint. The gluteal tuberosity is a roughened area that becomes continuous with the linea aspera, a ridge to which multiple muscles of the hip and thigh regions attach.
Furthermore, the intertrochanteric line and the intertrochanteric crest connect the greater and lesser trochanters anteriorly and posteriorly, respectively, and provide attachment points for the hip joint capsule and muscles.