Photo 1-3: The bridge Ponte Luiz I crossing Rio Douro, Porto
This might resemble the construction of the Eiffel Tower. Maybe Téophile Seyrig was inspired bu Gustave Eiffel, as they were business partners.
Photo 4: Sunset over the bridge Ponte de Arrábida crossing Rio Douro, Porto
Photo 5: 25 de Avril Bridge (Original name was Ponte Salazar) crossing Rio Tejo
No it is not the Golden Gate Bridge in San Francisco, albeit they look a lot alike. This bridge was built in 1966, and the train deck (lower deck) was added in 1999.