Orval
One of the six Trappist Monisteries in Belgium, Orval was created in 1132 AD.  They brew one beer, a Belgian Pale style, but Brettanomyces late in the process.  This addition of bacteria creates a beer that will ever evolve on its own.  When fresh, it’s malty, some hop bitterness, more than many Belgian brews.  Then, with time, the beer transforms, becoming more sour as the Brett attenuates the beer further, hops levels fall over time, changing the characters of this brew.