The title "Queen of Portugal" refers to the female monarch who ruled Portugal or was married to a king. The most notable queens include Queen Isabel, known for her charitable works, and Queen Maria II, who reigned during the 19th century and played a significant role in the country's constitutional development. Portugal had a monarchy until the establishment of the Portuguese Republic in 1910. The last reigning queen was Queen Amélie, who was married to King Carlos I. After the monarchy was abolished, the royal family went into exile, and Portugal transitioned to a republican government.