The official residence of the Spanish royal family — though they no longer actually live here, using it instead for state ceremonies and official functions.
Built on the site of a former Moorish fortress, the Palacio Real is Western Europe's largest functioning royal palace by floor area, with over 3,000 rooms — though only around 50 are open to visitors. The current royal family lives at the more modest Zarzuela Palace outside the city, keeping the Palacio Real for ceremony rather than residence.
The Throne Room, the Royal Armoury (one of the best collections of historic arms and armour in Europe), and the lavishly decorated state apartments are the highlights. The Royal Pharmacy and Royal Library are smaller but worth a look if you have time.
90 minutes to 2 hours for the self-guided route through the state rooms; add 30–45 minutes if you want to properly cover the Armoury.
A solemn changing of the guard takes place regularly outside the palace, with a more elaborate ceremonial version on the first Wednesday of the month (weather and royal schedule permitting) — worth timing your visit around if it interests you.
The Almudena Cathedral sits directly next to the palace and is worth combining into the same visit; Plaza Mayor and Sol are a short walk east.