  Accurate molecular crystal structure prediction is a fundamental goal in
academic and industrial condensed matter research and polymorphism is arguably
the biggest obstacle on the way. We tackle this challenge in the difficult case
of the repeatedly studied, abundantly used aminoacid Glycine that hosts still
little-known phase transitions and we illustrate the current state of the field
through this example. We demonstrate that the combination of recent progress in
structure search algorithms with the latest advances in the description of van
der Waals interactions in Density Functional Theory, supported by data-mining
analysis, enables a leap in predictive power: we resolve, without prior
empirical input, all known phases of glycine, as well as the structure of the
previously unresolved $\zeta$ phase after a decade of its experimental
observation [Boldyreva et al. \textit{Z. Kristallogr.} \textbf{2005,}
\textit{220,} 50-57]. The search for the well-established $\alpha$ phase
instead reveals the remaining challenges in exploring a polymorphic landscape.
