Complex sentence: The company employed Duvel and Butilia, who were students of Gustave Eiffel, the famous engineer who had built the Eiffel Tower and Garabit viaduct in France and the Dona Maria Pia railway bridge in Oporto, Portugal.
Split into simpler sentences: The company employed Duvel and Butilia, who were students of Gustave Eiffel. The famous engineer who had built the Eiffel Tower and Garabit viaduct in France and the Dona Maria Pia railway bridge in Oporto, Portugal.