What is the capital city of Spain?

The capital city of Spain is Madrid. Madrid has held this status since the 16th century when it was chosen for its central location, making it an ideal political and administrative center. The city is not only the political heart of Spain, housing the Royal Palace and the headquarters of government, but it is also a major cultural and economic center. Madrid is known for its rich history, art museums like the Prado, and vibrant lifestyle.

The other cities in the choices, such as Barcelona, Valencia, and Seville, while significant and known for their own unique cultures, histories, and economic contributions, do not serve as the capital of Spain. Barcelona is the capital of the Catalonia region, Valencia is an important coastal city and regional capital, and Seville is the capital of the Andalusia region. Thus, Madrid is distinctly recognized as the capital city of the entire country.