My recent article: G.Sardanashvily, “Lecture on Gauge Gravitation Theory. Gravity as a Higgs Field” in arXiv: 1602.06776
Gravitation
theory is formulated as gauge theory on natural bundles with spontaneous
symmetry breaking where gauge symmetries are general covariant transformations,
gauge fields are general linear connections, and Higgs fields are
pseudo-Riemannian metrics.