Clérigos Church, an 18th-century baroque building topped by the nearly 250-foot Torre dos Clérigos (or Clérigos Tower), offers unrivalled views of the Douro River and Porto's old town. The Torre is the tallest bell tower in the city and boasts 49 resonant bells. The structure also houses a museum, the House of the Brotherhood, with artifacts related to the clerics who founded the church.

While the museum and church are generally deemed worth seeing, the sweeping city views from the tower are what travelers deem as the best part of the visit. Note, there are more than 200 steps to climb to reach the top, so it takes some effort see the sights and snap your photos. Also note that this is a popular spot and the viewing area can get crowded. As such, many recommend heading here early so you won't have to deal with too long of a line, if any.

There is no charge to enter the church, but there is a 6 euro (around $6.70) admission fee to climb the bell tower. The church is open daily from 9 a.m. to 7 p.m. It can be reached by metro on line D to the Aliados stop, by tram on line 22 to Carmo stop and by bus lines 6, 20, 35, 37, 52 and 78. The tower only remains open in the evenings until 11 p.m. For more information, visit the official website.