This “mémoire” summarizes my research activity in the field of computational chemistry, starting from the PhD Thesis (i.e. from 2007) up to now and it indicates its future directions. The whole research work could be divided in five distinct scientific topics (Catalysis, Protein Allostery, Natural and Artificial Photosynthesis, Photochemistry, and Theoretical Spectroscopy), where various advanced computational techniques have been applied and original approaches have been developed. My scientific “adventures” are reported in a quasi-chronological order, following the various steps of my academic “travel” so far, with description by highlights of the most relevant results. The increasing power of available software and hardware resources, with potential revolutionary speed-up coming from the development of quantum computers, gives rise to a widespread use of computational models for the microscopic rationalization of chemico-physical problems at heart of big scientific questions. Considering computational experiments as a branch of science complementary to basic theory and laboratory experiments is becoming largely accepted, with recognition of the explanatory and predictive capacities of computational chemistry that supplement experiments with information not available otherwise.