Seia is a municipality located in the Guarda District of Portugal. It was officially elevated to city status on July 3, 1986, which also serves as the date for its municipal holiday. The city is situated on the northwestern slope of Serra da Estrela, which is the highest mountain range in mainland Portugal, reaching a peak height of 1,993 meters.
As of 2021, the municipality covers an area of 453.69 square kilometres with a total population of 21,755, while its urban population is approximately 7,000. The city hosts an annual cinema festival known as CineEco, which specifically features films centered on ecological and natural themes.