Several intriguing results were delivered by space and ground observations of 3C 273. First, the shuttle movement of the apparent core at 7 mm was discovered. A self-referencing method was used to show that two independent regions in the jet of 3C 273 accelerated/decelerated simultaneously which can only be ascribed to the movement of the apparent core by 4.4 pc, deprojected, in 5 months. It was shown that the position of the core correlates with its flux density during a major flare, which is expected if the flare is due to increase in electron density. Second, the apparent core appears more complex than a single Gaussian feature. A transition from opaque to transparent emission along the jet at its apparent base was resolved in 3C 273. The smooth transition extends by several parsecs along the jet and favors the opacity-related description of the apparent core. Measuring the extent of the transition region allows accessing the evolution of the B-field and particle density along the jet. Third, the substructure of refractive scattering was discovered in 3C 273 at 18 cm in observations with RadioAstron. It may affect the estimates of the brightness temperature and should be accounted for. These studies may be extended onto a sample of AGN.