Screenshots thanks to Rob Turner.

Castle Entrance
This is where Soma and Mina end up after they step through the shrine gate. Mina will wait here throughout the course of the game - although she doesn't do anything more than giving tips on where to go, at least she manages to not get herself kidnapped. Hammer will also set up shop here once you find him.

Castle Corridor
The usual entrance hallway is actually pretty large - though there's a straightforward path to the Chapel, there's still a lot of ground to explore in case you want to find some extra equipment.

Chapel
Though it's missing the nice scrolling clouds effects from Symphony and Harmony, the chapel is still filled with large, spacious rooms to climb. In the center area you'll fight the Manticore, though the upper region is occupied completely by a series of dancing spectres.

Study
It's the usual library-type area, filled with minotaurs and ectoplasms. Beat the knight boss here and you'll gain the precious double-jump ability.

Dance Hall
A silly little waltz plays as Soma fightings through more marble hallways. Take note of the painting in the right screenshot - it's the same as the Game Over screen. Below the ballroom is the wine/meat cellar, where you'll find the rock monster boss. Once you clear this area, you'll also meet Hammer, who will sell you stuff if you head back to the castle entrance.

Inner Quarters
The decor is here much like the final level of Castlevania Chronicles, right down to the insane ninja maids. You'll find a rabbit that will warp you to the past - there's nothing to do with him at the moment, so don't worry about it. Instead, beat the Headhunter boss and continue on.

Floating Garden
Similar to the Lost Woods in the original Legend of Zelda game, the floating garden features several hallways who seem to warp around one in another. If you wish to make progress, don't turn around - simply keep heading left to get to the clock tower, or right to get to the area with the black mist door. Remember this - once you've accomplished some of your important goals, you'll need to come back here.

Clock Tower
A Castlevania without a Clock Tower wouldn't be a Castlevania game, I guess. The usual assortment of gears, harpies, medusa heads and spikes will challenge you, although it's nothing particularly new. The Grim Reaper awaits to do battle, after which you'll find the ability to swim. I guess Dracula still uses water to make the clocks work (useless fact - this was invented by the Chinese.) How environmentally conscious.

Underground Waterway
You thought that boatman was a crazy old rambling coot, but when he's not around you see the result - crazy canoes out of control, crashing down waterways. This area is one of the first that you can access, but you can't really go anywhere until you gain the ability to swim. This will lead you to the underground cemetary.

Underground Cemetary
This is a little creepy here - Soma seems to be ruining a parade of colorless men that seem perfectly harmless - until you realize they're just part of the Legion boss at the end of the area. You'll obtain the Galamoth soul after you beat it and can finally get past that rabbit.

The Arena
This is pretty much just like the colliseum in Symphony of the Night, though thankfully much easier than the hellish trials of Circle of the Moon. Right before you descend the elevator to the boss, you are given the option of enterting on the three challenge rooms, which are large streams of enemies constantly attacking you, like the horde of beam skeletons in the screenshot on the right. Make it through alive and you'll snag some nice items. It's also good to level up for a fairly difficult fight with Balore. Once you make it out alive, you'll get the bat soul.

Forbidden Area
It's been awhile since we've seen a ghost ship in a Castlevania game, so that's pretty cool, but otherwise the only interesting thing about the forbidden area is that its hidden is rather hidden. The first time you're likely to come across this area, you'll hit a locked door. This is actually the exit. To get in, you'll need to get past the waterfall in the Underground Waterway (get the Kali soul.) Inside you'll find plenty of great loot, and one of the necessary books.

Top Floor
This is it - the final area. Only with the flying bat soul can you make the trek past all of the walking guards, succubi and other demons that prevent you from your final meeting with Graham.

Chaos Realm
This should all look pretty familiar - you'll run across many different rooms, although their layout is pretty...well, chaotic. One time you'll exit the screen and come across empty space. Another, you'll be walking through the castle corridor and end up in the underground waterways. Even with the lack of a map, it's pretty linear, and just leads up to the final boss.