Benjamín has a long career and is an important figure in the architectural history of Kópavogur. His legacy includes the organisation of both the town center of Kópavogur and Kópavogstún, designing Kópavogur Community center and Gerðarsafn, Kópavogur Art Museum, and many apartments and apartment buildings such as Hamraborg 14-38, Álfatún 27-35, Vogatunga, Sæból 26-30, Hlíðarhjalli 51-76, Trönuhjalli 7-11, Lautarsmári 1-13 and 27-53 and Vindakór 14-16.