In 2008 or so, I ran a Planescape game for Dungeons & Dragons 4th Edition. Below are links to crib notes explaining the setting to the players who were unfamiliar with the original TSR publications.
» Planescape 101: The Dark For Clueless Berks
» Sigil’s Wards & Districts
» Planar Cant (Sigil Slang)
» Services In Sigil
The Cosmic Planes…
» The Great Outlands(Mortal Worlds, The Feywild, The Shadowfell and The Underdark)
» Inner Planes of the Elemental Chaos
» Outer Planes of the Astral Sea
» Themes Across The Planes
Alternate Planar Map
A proposed change to the “Great Wheel” concept, here putting the whole Prime Material Plane as one massive planet, with the elemental planes “inside” and outer planars in orbit as “planets” – something more akin to the Spelljammer setting.
» The Great Big Cosmic Map (400k jpg)