The Event Horizon Telescope (EHT) is a global milimeter-wave interferometer able to observe the universe at an angular resolution of a few tens of micro-arcseconds. Such an extreme resolution, combined with the high observing frequencies (needed to overcome the strong opacity effects that are present in the cores of AGN), allowed us to reconstruct the first image of the surroundings of a supermassive black hole: an horizon-scale ring-like structure at the central engine of the active galaxy M87.

In this talk, we will review the historical EHT results of M87, discuss more recent findings on other AGN, and give some updates about the current ongoing projects in the EHT Collaboration.