Plaza de Armas (= Armament Square) is the main plaza in Iquitos. It is a couple of blocks from the water front. The square is a popular place for locals and tourists alike to gather, and within easy reach are a number of restaurants, hotels and souvenir shops. Some days, artists gather to show off their work or processions pass by to celebrate local festivals.
The "Iron House" on Plaza de Armas, Iquitos, was designed by Gustav Eiffel (who also designed the Eiffel Tower and the Statue of Liberty). On the ground floor of the Iron House is a cafe at which you can buy soft drinks, coffee and pastries. The top floor has a bar/restaurant with nice views of the Plaza de Armas. Down the street to the right is Mad Mick's souvenir shop, run by an (apparently sane) Englishman. The three-wheeled motocarro in the foreground is the main form of transport in the city, and you can get virtually anywhere for less than a dollar.
This glorious church on the southwest corner of the square has been recently renovated and represents one of the city's most spectacular architectural accomplishments (of which there are not very many!).