Fermat's Last Theorem
An English mathematician named Andrew Wiles found a solution in 1995, 358 years after Fermat wrote about it. Richard Taylor helped him find the solution . The proof took eight years of research. He proved the theorem by first proving the modularity theorem, which was then called the TaniyamaShimura conjecture. Using Ribet's Theorem, he was able to give a proof for Fermat's Last Theorem.  He received the Wolfskehl Prize from Göttingen Academy in June 1997: it amounted to about $50,000 U.S. dollars.