There is no silhouette more symbolic of Toledo than that of the Alcázar of Toledo. The commanding, square-shaped building - which is anchored by its four, sky-reaching corner towers - crowns the city, and has roots that reach back deeply into the ancient capital’s history.
While structures on this site date back to Roman times, the version you see today was largely erected in the 16th century under Carlos V, and has since been through many fires, reconstructions, and additions. Though it once served as home to royals (among other purposes), it now houses the country’s Military Museum, which offers an in-depth look at the nation’s past, complete with an impressive viewing terrace that overlooks the city.
While the museum is situated within the Alcázar, it doesn’t tour the fortress itself per se, so those keen to see the structure may be more satisfied just viewing it from outside. Note that the museum closes on Wednesdays, and is free to enter on Sundays.