The two cities of Porto and Vila Nova de Gaia face each other from opposite sides of the Douro river - Porto in the north bank and Gaia in the south. Six Pontes, or bridges, in total, join them. Of those, Ponte Dona Maria and Ponte Dom Luís, the two oldest ones, were built in the 19th century, respectively by Gustave Eiffel and by his partner in business, Théophile Seyrig. Ponte da Arrábida, Ponte de São João and Ponte do Freixo date from the 20th century, while the newest one, Ponte Infante Dom Henrique, is no older than the 21st century.
