It is always a bit of a problem - what to do with buildings that have outlived their original purpose, especially if they are of historical value to the nation to which they belong. There is hope for one set of - albeit quite peculiar - buildings off the coast of the United Kingdom.
From the article
The Maunsell Sea Forts occupied positions in the Thames and the Mersey estuaries during World War Two. The rivers were vital in terms of transporting food and the vital equipment needed to sustain the beleaguered island and were designed to protect the two most important ports in the United Kingdom - those of London and Liverpool.