The Red Rectangle is a spectacular bipolar nebula centred around the eccentric evolved binary HD 44179. The nebula is rich in spectral signatures: it is the brightest source of the Extended Red Emission (ERE), of the Blue Luminescence (BL) as well as one of the brightest sources of mid-IR PAH bands. Moreover, and unique to this source, a plethora of narrow emission lines is detected on top of the diffuse ERE. Some of these molecular features show rotational contours which become narrower at larger angular separation from the central engine. Some converge to wavelengths and profiles of narrow DIBs. All these observations show that the Red Rectangle is a very rich laboratory to study active astrochemical processes within the nebula. We also address, but fail to answer, the question why this source is so unique among the many observed post-AGB binary analogues.
