Built on the former site of a Benedictine monastery, the São Bento Railway Station was inaugurated in 1916; today, trains pass through here carrying travelers between Porto and many of its northern suburbs. But you likely won't be visiting here to hop a train anywhere. What's notable about this landmark is its 20,000-some painted blue and white tile panels (known as azulejos) that highlight the history of Portugal. Portuguese artist Jorge Colaço is the mastermind behind this azulejo piece; its tiles were mounted over the course of a decade — from 1905 to 1916. Some of the most impressive scenes include King João I and Queen Philippa standing near the city's cathedral in 1387 and a depiction of the Battle of Arcos de Valdevez.

While it may seem unusual to see such detailed artwork in a train station, one TripAdvisor user goes as far to say a visit to Porto just isn't complete until you step inside. "The architecture and beautifully painted tiles speak to the heavy religious influences in Porto. Take your time and enjoy … the clock and the intricate steel structure once inside too."

You'll find the São Bento Railway Station just southeast of Avenida dos Aliados, so planning to visit these two sites together makes the most sense. (You should time your visit outside typical rush hour to avoid too many crowds.) The rail station is accessible via the São Bento metro stop on the D (yellow) line, and entry is free. Find more information on the São Bento Railway Station, including train schedules and tickets, by visiting its website.