Concrete in the core portion of the gigantic Hoover dam in Nevada, USA is still continuing to cure according to engineers. That is in spite of the fact that the dam was built way back in 1935 and a huge network of 1 inch dia. pipes totalling to a length of almost a thousand kilometers was buried inside the concrete to circulate cold water in order to suck the enormous heat of hydration generated by the huge quantity of poured concrete.

So that was not good enough to stop it from curing even today and in fact, this is expected to continue for some more years.