Sé Cathedral / Porto Cathedral

Perched on a hilltop standing watch over the city, the Porto Cathedral was originally built between the 12th and 13th centuries, and features a variety of architectural styles, including Romanesque, baroque and gothic. The fortress-like church is the largest in the city and one of Porto's oldest monuments; it's flanked by twin towers and has a rather plain stone facade. But inside the Sé you'll find a beautiful stained-glass rose window, a collection of centuries-old sculptures and a silver altarpiece that was once used as the bishop's study. Meanwhile, the cloister boasts cobalt and white ceramic tiles that depict different scenes from religious history. Most travelers say visiting the church and cloister is absolutely worth an hour or two, noting that the exterior is remarkable but the interior is exquisite.