The Heroes of Olympus

The second series of Percy Jackson books by Rick Riordan

The Blood of Olympus

Trials Of Apollo

What order should you read the "Trials Of Apollo" books? The brilliant fantasy series by Rick Riordan

The Hidden Oracle - The Trials of Apollo book 1
The Dark Prophecy - The Trials of Apollo book 2
The Burning Maze - The Trials Of Apollo book 3
The Tyrant’s Tomb - The Trials Of Apollo book 4
The Tower of Nero - The Trials Of Apollo book 5