Mozart's 'Ave Maria' K. 554, originally a vocal work, is a beautiful and devotional piece often transcribed for piano. It is characterized by its serene melody and elegant harmonic progressions.
Achieving a pure, singing tone and a seamless legato line with sensitive pedaling are crucial for this devotional piece.
"Ave Maria" K. 554 is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 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.
A typical performance of "Ave Maria" K. 554 lasts about 3 minutes.
"Ave Maria" K. 554 is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.