This famous keyboard work from Handel's Suite in G minor consists of a somber theme followed by intricate variations. It is distinctive for its dramatic harmonic shifts and rigorous contrapuntal texture.
Maintaining a steady pulse while executing consistent articulation across the variations is the primary challenge.
Comparable difficulty and character — good candidates for what to learn next.
Passacaglia is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 8.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 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 Passacaglia lasts about 3 minutes.
Passacaglia is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Sarabande by George Frideric Handel, Prelude in C-sharp minor, No. 2 by Sergei Rachmaninoff, Ballade by Sergey Lyapunov — see the full similar-pieces list on this page.