  The rubble pile spin barrier is an upper limit on the rotation rate of
asteroids larger than ~200-300 m. Among thousands of asteroids with diameters
larger than ~300 m, only a handful of asteroids are known to rotate faster than
2.0 h, all are in the sub-km range (<=0.6 km). Here we present photometric
measurements suggesting that (60716) 2000 GD65, an S-complex, inner-main belt
asteroid with a relatively large diameter of 2.3 +0.6-0.7 km, completes one
rotation in 1.9529+-0.0002 h. Its unique diameter and rotation period allow us
to examine scenarios about asteroid internal structure and evolution: a rubble
pile bound only by gravity; a rubble-pile with strong cohesion; a monolithic
structure; an asteroid experiencing mass shedding; an asteroid experiencing
YORP spin-up/down; and an asteroid with a unique octahedron shape results with
a four-peak lightcurve and a 3.9 h period. We find that the most likely
scenario includes a lunar-like cohesion that can prevent (60716) 2000 GD65 from
disrupting without requiring a monolithic structure or a unique shape. Due to
the uniqueness of (60716) 2000 GD65, we suggest that most asteroids typically
have smaller cohesion than that of lunar regolith.
