Seville's Cathedral

Seville's Cathedral is massive. At 124,000 square feet, it is the largest cathedral in the world. There are two larger churches (including St Peter's basilica in Rome) but neither are cathedrals. It is a really amazing structure, and dwarfs the other cathedrals I have been to.

The Cathedral is also home to the largest altar piece in the world. It stands some 65 feet tall.

It is also home to tomb of Christopher Columbus. Columbus has four pall bearers, representing the four kingdoms of Spain that sent him off- Castille, Aragon, Navarre, and Leon. A spear sticks into a pomegranate (Granada in Spanish), representing the kingdom of Granada that was taken in 1492 as the last stage of the Reconquest.

The most impressive, though, in my opinion, is the most expensive crown in Spain. On the crown you can see the world's second largest pearl.
The one in the middle on the top looks kind of dinky right? There's no way that could be the one.
Look again. The cherub on the front of the crown has his entire body carved from one single pearl! There's no telling how large it was before it was carved.