Gillis Haanen, just like his younger sister Elizabeth Alida, made a name for himself by painting interiors and churches in sunlight, candlelight and lamplight, with a great eye for detail. A subject with which his father Casparis Haanen also gained fame. But he also painted beautiful, romantic cityscapes and landscapes, including some together with his brother Remigius Haanen and J.W. Bilders. Gillis Haanen traveled extensively in Germany, Belgium and Austria and lived in Cologne for a longer period between 1854 and 1860.