Let's Talk Biggest!

 The Seville Cathedral is the largest Gothic cathedral in the world and the third largest temple in size after St. Peter's Basilica of the Vatican in Rome and St. Paul in London. Another UNESCO site. 

Seville Cathedral with the Moorish Bell Tower

Giralda Bell Tower
Built in 12th Century, it is 104 meters tall.
  It has ramps instead of stairs inside so the muezzin could ride a horse to the top for the call to prayer.

Christopher Columbus's grave

A very very trippy floor

Capilla Mayor
Largest altar piece in Christendom.

The Metropol Parasol, popularly known as Las Setas de Sevilla (the Mushrooms of Seville) is the largest wooden structure in the world.  It was created in 2011.  You can take an elevator to the top and walk along a walkway up the whole length of it.  At night, there are multi-colored lights.  If I had planned ahead, I could have gotten evening tickets, but alas...

Lunch