One of the most fundamental stellar parameters, mass, is often unavailable or measured with low accuracy, leading to weak constraints on stellar structure and evolution. Observing binary stars through a combination of interferometry and spectroscopy provides a unique opportunity to obtain highly precise dynamical mass measurements. Additionally, double-lined spectroscopic binaries offer independent distance measurements with extreme accuracy, enabling direct tests of Gaia parallaxes. I will demonstrate that by combining interferometric and spectroscopic observations, masses and distances with accuracy levels as high as 0.05% can be achieved for various types of binary systems, including binary Cepheids, eclipsing binaries, and standard binaries.