If you're not familiar, the "Before" trilogy follows a love story in three films spaced nine years apart that feature the same two actors. We watch these actors age, starting when they meet and fall in love in 1994's Before Sunrise, reunite in Paris is 2003's Before Sunset and negotiate their marriage and lives as the parents of twins in 2013's Before Midnight.
The "Up" series -- which the late Roger Ebert called "the noblest project in cinema history" -- also takes us on a real journey through time. The documentary series began with 7 Up in 1964 and follows fourteen 7-year-old children from diverse socio-economic backgrounds in 1960s Britain. A new documentary has come out every seven years since -- the most recent is 56 Up.
These movies provide an unusual and revealing look into the nature of life and time. (See also Harry Potter series.)