When we began these bi-weekly round-ups of readers' comments back in October, we did so with one key aim: to encourage open, democratic debate with a very low barrier for entry - the type of internet-enabled debate that many architecture critics and publications have given up on. This week, we got a taste of just that kind of rational, professional debate as our readers picked apart the popular opinion in the wider media that the renovation of Cádiz Castle was "a perfect example of how not to restore an old castle." Alongside debates on whether architecture is a form of art and what the AIA should be doing about sustainability, read on to see what our readers had to say after the break.

After built structures become disused or abandoned, adaptive reuse can be the perfect way to breathe new life into an old building, while conserving resources and historic value. Whether due to environmental reasons, land availability or the desire to conserve a historic landmark, countless architectural firms worldwide are turning to adaptive reuse as a solution to some of the modern problems of the built environment.

With this in mind, we have compiled a list of 20 creative adaptive reuse projects, each of which utilizes an old structure to create a revitalized form in its own distinct way.

See how a former chapel, water tower and 19th century slaughterhouse were transformed and given new life, after the break.