From Olrox's Quarters, head right into the Royal Chapel. This area is characterized by its stained-glass windows and numerous religious-themed enemies like Priests and Spirits. The main challenge here is navigating the bell towers. You'll need to use your Bat form and double jump extensively to reach higher platforms. Be careful of the spectral swords that fly around.
Your primary objective is to find the Holy Symbol relic. This item grants Alucard temporary invincibility when he falls into water, preventing damage from the spikes often found at the bottom of water pits. The Holy Symbol is located in a room accessible by breaking a wall in the upper-right section of the chapel. There's also a Save Room and a Teleporter in this area, making it a good hub for exploration.