If you’re visiting Lisbon it’s very likely that at some point you’ll hit the Praca do Comercio, the historical commercial center of Lisbon. Lots of things to see and do in the area, and the plaza is spectacular, but to really be able to experience it you should head up the Rua Augusta Arch and look at it from above. Originally a bell-tower intended as a memorial for the massive 1755 earthquake it was transformed to an imposing arch and features grand sculptures of Glory honoring Valor and Genius. Tourists can take the elevator from the first floor up. When I visited it was rainy and gloomy, so I was the only person there, which was terrific.
Be sure to go up there if you’re visiting the Plaza in Lisbon. These are views worth seeing.