In tetragonal SrCo<sub>2</sub>As<sub>2 </sub>single crystals, inelastic neutron scattering measurements demonstrated that strong stripe-type antiferromagnetic (AFM) correlations occur at a temperature T = 5 K [W. Jayasekara et al., arXiv:1306.5174] that are the same as in the isostructural AFe<sub>2</sub>As<sub>2</sub> (A = Ca, Sr, Ba) parent compounds of high-T<sub>c</sub> superconductors. This surprising discovery suggests that SrCo<sub>2</sub>As<sub>2</sub> may also be a good parent compound for high-T<sub>c </sub>superconductivity. Here, structural and thermal expansion, electrical resistivity ρ, angle-resolved photoemission spectroscopy (ARPES), heat capacity C<sub>p</sub>, magnetic susceptibility χ, <sup>75</sup>As NMR and neutron diffraction measurements of SrCo<sub>2</sub>As<sub>2</sub> crystals are reported together with LDA band structure calculations that shed further light on this fascinating material. The c-axis thermal expansion coefficient α<sub>c</sub> is negative from 7 to 300 K, whereas α<sub>a</sub> is positive over this T range. The ρ(T) shows metallic character. The ARPES measurements and band theory confirm the metallic character and in addition show the presence of a flat band near the Fermi energy E<sub>F</sub>. The band calculations exhibit an extremely sharp peak in the density of states D(E<sub>F</sub>) arising from a flat d<sub>x<sup>2</sup>-y<sup>2</sup></sub> band. A comparison of the Sommerfeld coefficient of the electronic specific heat with χ(T → 0) suggests the presence of strong ferromagnetic itinerant spin correlations which on the basis of the Stoner criterion predicts that SrCo<sub>2</sub>As<sub>2</sub> should be an itinerant ferromagnet, in conflict with the magnetization data. The χ(T) does have a large magnitude, but also exhibits a broad maximum at 115 K suggestive of dynamic short-range AFM spin correlations, in agreement with the neutron scattering data. The measurements show no evidence for any type of phase transition between 1.3 and 300 K and we propose that metallic SrCo<sub>2</sub>As<sub>2</sub> has a gapless quantum spin-liquid ground state.