Its location and its natural conditions have always been the reason for the settlement of populations in this region, finding traces of occupation since the prehistoric times, in several places in the county.

Of these traces of occupation, one of the most important is the Roman city of Miróbriga, Romanized from the first century BC until the fifth century AD. During this period it became the main Roman city on the western coast south of the Tagus, where there was a forum with its temples, baths and the only Roman hippodrome known in Portugal. Even today, the archaeological site of Miróbriga is one of the most important tourist attractions in this region.

It was around the 8th century that the Moors reached the territory, building the castle on the hill in front of the Roman city; it is even thought that the name Kassem (Cacém) is linked to the tribe that dominated this region: the "ben Kassim".

The Islamic occupation ended in 1217, when it returned definitively to the possession of Christians, having been donated by the King Afonso II to the Order of Santiago da Espada.The medieval village of Sant'Iago de Kassem was already of great importance in the 13th century, and between 1315 and 1336, by donation of the King D. Dinis, the village and castle belonged to the princess D.ª Vetácia Lascaris, Byzantine princess, aunt and friend of the Queen Saint Isabel, and who lived here, having left here some unique pieces, such as the low relief of "Santiago fighting the Moors", a masterpiece of medieval sculpture and the relic of the Holy Cross.

 It returned to the Order of Santiago after his death and became the county seat in 1512, when it was granted a charter by King Manuel I.After the remarkable urban expansion it presented in the 18th century, the county asserted itself in the region during the French invasions, seeking to concentrate in the Melides/Comporta/Alcácer area as many armed men as possible, and some people connected to the House of Santiago played crucial roles in this resistance, namely José Máximo Coelho Falcão, whose portrait can still be found in the house, and Carlos José Luzeiro de Reboredo, 5th grandfather of the current owners.

This entire region is essentially agricultural, with a variety of landscapes and cultures almost unique in the country, producing cereals, fruit, cork and livestock, in a county that combines the proximity of the beach, the nearest being about 10 minutes away, Melides being 15 minutes away and Comporta 30 minutes away, with a landscape of great variety and scenic beauty.In Santiago do Cacém and its surroundings there are perfect places for surfing, diving, trekking, biking, horseback riding, motocross, hunting and fishing, as well as excellent producers of fruit and traditional sweets, handicraft, restaurants and monuments that are worth a visit.The historical center of Santiago do Cacém, with the castle, the main church of Santiago Maior and a unique set of manor houses, the Roman ruins of Miróbriga, with its views, the farms around the city, excellent examples of farms of the recreation of the eighteenth century, are some places to visit.