A themed PCCP issue with a collection of articles on “Electron delocalization and aromaticity: Celebrating the 150th Anniversary of the Kekulé Benzene Structure” has been edited by Prof. Dr. Gabriel Merino from CINVESTAT (Mérida) and Miquel Solà from the Institute of Computational Chemistry and Catalysis (IQCC). These researchers have written the corresponding editorial and designed the front cover. The collection gathers about 40 papers on subjects related to molecular aromaticity. Among them, we can find a paper from Dr. Eduard Matito, ex-IQCC member, on a new measure of aromaticity for large systems and a paper on octahedral aromaticity by current IQCC members Ouissam El Bakouri, Ferran Feixas, Miquel Duran, and Miquel Solà together with Jordi Poater, an ex-IQCC member.