Ok, time for the first WIP.
The matte will be an establishing shot of Thyn, a fantasy-like city with a castle built partially into a cliff (actually, a place from one of my own pen-and-paper RPGs I wrote years ago). In general, desert/rock environment, in a mood of "Prince of Persia" or "Scorpion King". Final shot will be a 3D matte with multiple projections to cover long camera move - it will fly over the desert and circulate a bit around the city. The whole animation will be about 16 seconds, so quite long and quite a bit of work :) Additionally, some effects will be added like smoke from various chimneys and some movement (caravan approaching city gates, cranes on the city wall). The final comp will have, of course, things like moving clouds, sun rays and other stuff.
OK, enough for the intro. Here's a first rough scene blockout and camera movement.
Here some simple city buildings that will be multiplied and create base for city projection. They will have procedural shader applied that will serve as a starting point for the matte.