Fame gives celebrities a taste of immortality, but after seeing the spitting image of some A-listers in photographs from the distant past (and noticing that Rob Lowe never, ever ages), we've begun to wonder if some stars really do shine forever. Sylvester Stallone's doppelganger lurks in a 16th century fresco painted by Raphael in Vatican City; a man who looks like Nicolas Cage was found in a Civil War-era picture; a young man photographed in Harlem in 1939 bears a striking resemblance to Jay-Z. What's their secret to eternal life -- Vampire bites? Illuminati conspiracy? Time travel? We cooked up some (slightly outlandish) theories of our own.