Built in the 13th century at the behest of King Afonso III, it is one of the largest and most emblematic monuments of mendicant Gothic architecture in Santarém. During the 17th century, it underwent several renovations that modified its form. Currently, the eight rows of tall Gothic columns adorned with frescoes and carved capitals stand out, with lighting provided by a rose window and several windows and slits. Inside, the Gothic tomb of the founding king's illegitimate daughter is a prominent feature.

It is located on the first floor of the Municipal Library building, which originally housed the palace of the Barons of Almeirim, a characteristic Ribatejo mansion remodeled in the 19th century. This Museum Centre presents an important artistic and bibliographic collection, highlighting collections of painting, furniture, decorative art and sculpture, in addition to an interesting and unusual bookstore. Collections from the Camões Library and a collection of contemporary art can also be seen.

The Open-Air Museum is the ideal place to learn about the history of the municipality of Campo Maior and its people, from prehistory to the present day, without forgetting its ongoing connection with Spain.

The castle was rebuilt by King Dinis in 1310 and underwent restoration work in the 18th century. Of the old fortification, situated atop a hill, only some sections of the wall and towers remain, in addition to the 17th-century fortifications, with escarpments, parapets, and ravelins, built during the Restoration War. The Church of Our Lady of Grace stands out, with its gable façade, framed straight lintel portal, and oculus. This castle is a characteristic example of the border fortresses of lowland regions, with a bastioned system determined by pyrotechnic artillery.

Prehistoric archaeological site, where excavations uncovered megalithic monuments.

A museum space inaugurated in 2005 that promotes and preserves the history of olive growing. It shows the process of cultivating and harvesting olives, up to their transformation into olive oil.

The Portas da Vila, also known as Portas de Santa Maria, are one of the most characteristic monuments of Campo Maior, and also one of the main entrances to the town.

A 17th-century palace with proto-Baroque and Baroque architecture. It has a Baroque garden with a fountain and pavilion decorated with vegetal and shell-shaped stucco elements.

Built between 1570 and 1646, it has a tripartite main façade with embedded pilasters. The central part features a wide round arch forming a narthex, surmounted by three windows with three pediments. On the sides, two strong bell towers covered by domes are visible. Inside, with three naves, the silver liturgical objects and vestments woven and embroidered with gold from the 16th century stand out. It is also known as the Church of Our Lady of Expectation.

Built in 1766, the Chapel of Bones, also known as the Chapel of Souls, is attached to the main church. The interior decoration features human bones, a tribute to those who died in the 1732 catastrophe, which killed 2/3 of the village's population.