The Poblado de Alfonso XIII is a hamlet that belongs to the municipality of Isla Mayor. Isla Mayor began to be populated in the early 20th century by rice farmers. From the 1940s onwards, immigrants from other parts of Andalusia, Extremadura and the Levante came to make a living from agriculture. In 1994, Isla Mayor was administratively separated from Puebla del Río.
The hamlet of Alfonso XIII sits to the north of the urban centre of Isla Mayor. The parish of Our Lady of Carmen is the largest building. King Alfonso XIII himself laid the foundation stone of this temple in 1928. A fair in honour of Our Lady of Carmen takes place on 16 July.
This hamlet is an ideal place for birdwatching, as is the town of Isla Mayor and the surrounding area.