The prehistoric temples of the Maltese islands, built entirely of the local limestone, are today considered as the world's first free-standing monuments in stone. Restoration works were carried out within these temples in the past as the need arose. These works ranged from the simple re-erection of fallen blocks, to the widespread capping of the megaliths of one temple complex with concrete. A number of unique decorations found within these temples were also moved indoors shortly after being discovered. Cracks and fissures were usually filled in with Portland cement or 'deffun', a cement made out of lime and powdered pottery. Iron or bronze dowels were also used on occasions. Surface treatment of weathered stone was also carried out for a number of years. This consisted of the application of linseed oil in paraffin to deteriorating blocks. Unfortunately some of these measures have not only been unsuccessful in treating the original problem, but have given rise to additional problems. These restoration methods have now all been stopped and are being re-evaluated and modern methods of conservation sought by the Stone Research and Conservation Laboratory recently set up within the Museums Department for this purpose.