The name Valigium is believed to date back to the Lombard era — an idea closely linked to the popular legend of the Via Regia, the ancient Roman road traveled in 590 by Queen Theodolinda and her husband Agilulf, Duke of Turin and later King of the Lombards. It appears certain that Queen Theodolinda, on her journey from Lomello to Milan, passed through Valeggio.

The austere and imposing bulk of its 13th-century castle is visible from afar, with its trapezoidal layout and seven asymmetrically arranged towers of varying shapes and sizes.

A necropolis with more than two hundred Roman-era tombs — the source of many of the archaeological finds now preserved in the Lomellina Archaeological Museum in Gambolò — was unearthed here.

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