We study strong light-matter coupling at terahertz frequencies employing a system based on an array of deeply subwavelength split ring resonators deposited on top of an ensemble of modulation-doped quantum wells. By applying a magnetic field parallel to the epitaxial growth axis, at low temperatures, Landau Levels are formed. We probe the interaction of the inter-Landau level transitions with the resonators modes, measuring a normalized coupling ratio Omega/omega(c) - 0.58 between the inter-Landau level frequency omega(c) and the Rabi frequency Omega of the system. The physics of the system is studied as a function of the metasurface composition and of the number of quantum wells. We demonstrate that the light-matter coupling strength is basically independent from the metamaterial lattice spacing. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4795543]