Complex sentence: The history and the story of the Maltese Islands was always close to Vella's heart and he had spent many years assisting Temi Zammit with various archaeological research, with a special focus on his hometown, Mosta.
Split into simpler sentences: The history and the story of the Maltese Islands was always very close to Vella's heart. He spent many years assisting Sur Temi Zammit with his various archaeological research, however always with a special focus on his own hometown, Mosta.