Quasars are the brightest (non-transient) objects observed at the highest redshifts, z>7. Such high redshift quasars are important for several reasons. Firstly, detailed analysis of quasar spectra provide unique information about the baryonic and physical condition of the Universe during the epoch of reionisation. Furthermore, the density of high redshift quasars puts powerful constraints on the mechanisms that are required to seed and grow >10^9 Msun supermassive black holes less than a Gyr after the Big Bang. Lastly, as these massive black holes are thought to be located in the progenitors of the massive early type galaxies we see in the local Universe, studying the host galaxies of the most distant quasars enables us to probe the formation of massive galaxies in the early Universe. Because high redshift quasars are rare, multi-band surveys covering large areas on the sky are required to discover such objects. In this talk I will describe our successful programme aimed at discovering quasars at the highest redshifts in various optical and near-infrared surveys, such as Pan-STARRS1, UKIDSS and VIKING. I will highlight the results of our search, which includes the discovery of more than 100 new quasars in the first Gyr of the Universe. I will describe our on- going multi-wavelength follow-up observations to characterise the distant quasars, their power source and their environment, in particular our ALMA programmes to study the galaxies hosting these luminous objects. I will present the results of these observations, and discuss the implications for massive galaxy and black hole formation at high redshift and our understanding of the relation between the black hole mass and the bulge mass of galaxies.