Johann Sebastian Bach's '16 Konzerte nach verschiedenen Meistern' are transcriptions of concertos by other composers, adapted for solo keyboard. These works showcase Bach's genius in reinterpreting and enriching existing musical material with his distinctive contrapuntal mastery.
The primary technical hurdle is navigating the dense contrapuntal lines and executing rapid passagework with clarity.
16 Konzerte nach verschiedenen Meistem is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
16 Konzerte nach verschiedenen Meistem is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.