Nice game.
I have one suggestion - when looking at cards in my hand, I'd like to see their "Available next to" info, too. Maybe show it when mouse over - either like tooltip, or highlight buildings on map next to the tile, that are providing availability for that building.
Currently the only possibility to find why this card is available at given tile, is to find that card in the Goal section at the right, and that's sometimes little bit tedious.