The dusty torus of an Active Galactic Nuclei (AGN) surrounds the accretion disc and supermassive black hole. This provides the angle-dependent obscuration that leads to the type-1/type-2 dichotomy. The dusty structure absorbs UV and optical light from the accretion disc and thermally re-emits it in the infrared. The dust sublimation sets the inner boundary which happens when the dust temperature reaches 1500 K, corresponding to near-IR emission. Thus, variability in the optical emission will be observed in the near-infrared with a time lag equivalent to the light-travel time between accretion disk and dusty torus. Here, we present optical-to-near infrared reverberation mapping of a sample of nearby AGN. We determine dust time lags to measure the physical size of the sublimation radius and test its relation to the AGN luminosity. This relation is currently being investigated as a new standard candle in cosmology and our measurements will allow for calibration of the Hubble diagram of AGN.