"Whether you’re religious or not, this old Dominican church will certainly bring you the enlightenment you’ve been seeking. After months of renovation this magnificent structure originally constructed in 1294 has opened its doors to the public as a “brand new” bookstore in the heart of Maastricht. A superb example of adaptive re-use, the Selexyz Dominicanen infuses rich and historic architecture with plentiful shelves ripe with information. Dating back to the 13th century, the structure was a Dominican church until Maastricht was invaded by Napoleon in 1794 and the group was forced out of the country. Since that point it has been briefly used as a parish, then a warehouse, then an archive, then a giant parking lot for bicycles (not such a terrible idea) and finally made over into a bookstore by the architecture firm Merkx + Girod." (c/o inhabit)

I'd like to nominate a few churches on both St. Clair and Roncesvalles for this adaptive re-use.