There are currently eleven bonus stages you can unlock (that I have found so far) in Soul Calibur 5 for the PS3 and Xbox 360.
Here are the eleven bonus stages, and how to unlock them. If I find more, I’ll be adding them to this list over time.
Ancient Citadel – Peacetime: Complete Episode 4 in Story mode, or reach player level 7
Astral Chaos – Crossing Points: Reach player level 25
Astral Chaos – Pathway: Fight Alpha Patroklos in Quick Battle mode, or reach player level 25
Conqueror’s Coliseum – Underground Fight: Reach player level 13
Denever Castle – Assualt: Complete episode 18 in Story mode, or reach player level 18
Denever Castle – Eye of Chaos: Beat Pyrrha Omega in Story mode
Last Rites on the Battleground: Complete episode 18 in Story mode, or reach player level 40
Penitentiary of Destiny: Beat Kilik in Arcade mode or Legendary Souls mode
Tower of Glory – Most Holy Dichotomy: Beat Angol Fear in Arcade mode or Legendary Souls mode
Tower of Glory – Spiral of Good And Evil: Beat Edge Master in Arcade mode or Legendary Souls mode
Unknown Forest – Dark Night: Complete episode 7 in Story mode, or reach Player Level 21
Utopia of The Blessed: Beat Elysium in Story mode
Check out my other article for the complete list of unlockables in Soul Calibur 5.