  The notion of a universal building associated with a point in the Hitchin
base is introduced. This is a building equipped with a harmonic map from a
Riemann surface that is initial among harmonic maps which induce the given
cameral cover of the Riemann surface. In the rank one case, the universal
building is the leaf space of the quadratic differential defining the point in
the Hitchin base.
  The main conjectures of this paper are: (1) the universal building always
exists; (2) the harmonic map to the universal building controls the asymptotics
of the Riemann-Hilbert correspondence and the non-abelian Hodge correspondence;
(3) the singularities of the universal building give rise to Spectral Networks;
and (4) the universal building encodes the data of a 3d Calabi-Yau category
whose space of stability conditions has a connected component that contains the
Hitchin base.
  The main theorem establishes the existence of the universal building,
conjecture (3), as well as the Riemann-Hilbert part of conjecture (2), in the
case of the rank two example introduced in the seminal work of
Berk-Nevins-Roberts on higher order Stokes phenomena. It is also shown that the
asymptotics of the Riemann-Hilbert correspondence is always controlled by a
harmonic map to a certain building, which is constructed as the asymptotic cone
of a symmetric space.
