Terahertz (THz) radiation locates between the infrared and microwave region of the electromagnetic spectrum. This region hosts a wealth of intriguing and highly complex interactions between radiation and matter. The recent development of coherent THz sources has opened the road to the THz time-domain spectroscopy (THz-TDS). The advantage of using such a spectroscopic technique resides in the possibility to access the amplitude and phase of the electro-magnetic field opening the road to novel investigations. Within the complex photonics group activities, THz-TDS is employed to study radiation transport in photonic glasses, for the characterization of THz devices and artificial THz materials such as photonic crystals and metamaterials, and even for imaging and spectroscopy of cultural heritage materials.