There are two clock towers in some games, that's probably what's messing you up.
CV1. Clock Tower is the tower the is holding up the keep.
Haunted Castle: The Clock tower is in the castle, but it is not holding up the keep like in cv1.
CV2. all in ruins, there are no towers.
CV3. One Clock Tower outside of town with a bridge that leads to the Castle. Bridge gets destroyed when you save Grant. 2nd Clock Tower is the one holding up the keep, and its largest chamber is the pendulums room.
CV4. Clock Tower is far from the keep and you need to cross a bridge to get to the keep's tower. Like in CV3, that bridge gets destroyed but unlike cv3, it breaks as you cross it.
CVX68000. Clock tower is, like cv4, far from the keep and you need to cross a bridge. This is actually very very similar to CV4.
CVA. None
CVA2:BR. None
CVL: Clock Tower is in the castle, but it's not close to the keep, like in CV4 and X68000.
Rondo: Clock Tower is in the castle, an amalgamation of CV1's location and CV3's location. You cross a bridge (that crumbles) to get to the tower this time, and the bridge is like CV1's. The Clock Tower's layout is similar to CV1's as well, only with a more vertical mode in mind. Like CV3 though, there's a large pendulums room that you use to get to the keep... but not before going to the Ceremonial Room with the Chalize and fighting a boss.
CVSotN: Layout it exactly like Rondo of Blood. The clock tower in the background of the keep, I guess, is the clock tower you just traversed, but that implies that the pendulums room is in face a very wide and long bridge area that leads to yet another tower where the ceremonial room is, which is the tower that holds up the keep...
...which means the SotN clock tower you see should have had a long bridge to the foreground instead of being all on its own the way it is. I guess they couldn't make it or just put it up by itself 'cuz it looks cooler. Or SotN has two clock towers and one you never cross, but that's just whacky.
DraculaXX: Like CV3's first clock tower, this one seems to be far from the castle, across a bridge. Why one would go all the way out there is beyond me. Perhaps searching for Death or Annette?
CotM: Machine Tower, but this is not Dracula's Castle (it's Carmilla's). It stands on its own on the left side of the castle. There is a connecting pathway between the three main towers though (Machine Tower, Observation Tower, and Chapel Tower), so at least this map matches the map's artwork.
Bloodlines: Just ruins in Dracula's Castle, no clock tower. The Munitions Factory is similar but it's very faaaaaaaaaaar.
CV64/LoD. The Clock Tower is the tower that is holding up not just the keep, but two other chambers (though the keep appears to be one large tower, not a floating room, so it's more like SotN, I guess. You exit the clock tower from one side (or from the clock's hands, if you're playing LoD) to the Keep's staircase. The Clock Tower's location is clearly defined, as it is in the center of four tall towers (but not as tall as it), on top of which you fight Death/Actrise/Ortega (the four towers appear to be the Tower of Execution, the Tower of Sorcery, The Tower of Ruins, and The Tower of Art (though the last two could be the Tower of Duels or the Tower of Science, but I don't think so because they should be lower down in the castle). While you battle on the top of these towers you can see the Clock Tower and the iconic staircase leading up, no matter what tower you're battling on. There is a bridge under the Clock tower, which leads to the Room of Clocks, which connects all of the towers together.
HoD: Clock Tower is in the castle, on the far right, somewhat like CV3's clock tower (but not really). The keep this time is held by the Chapel, and the clock tower connects to the chapel. The clock tower you see in the distance in the Keep should have had a bridge leading up to some more tower structures... but it doesn't. Like SotN.
Aria: This is the most interesting one because it's somewhat correct in its location with respect to everything else. When you're in the Clock Tower, you're on the right side of the map but the clock tower and the chapel have switched sides from Harmony's locations. The Clock is now the closest to the Keep, but the keep is held by its own tower. If you recall, there is a bridge that leads from the clock tower to the Top Floor (in the map), When you're at the Keep part of the Top Floor (under the staircase), you can actually see the bridge that connects the Top Floor to the Clock Tower.
Dawn: It's not Dracula's Castle, but rather Celia's (The cult's) castle. The Clock Tower connects to the Pinnacle. The 'keep' is held up by a tower in the Pinnacle, and you can see the Clock Tower in the distance. It's mostly correct.
Portrait: The "Tower of Death" is the Clock Tower. Its location is similar to that of CV3 and Rondo, but the Tower of Death stands alone, with no real connecting bridge to the Master's Keep (though the water tower has access... to the bottom... but so does the other side of the tower so it's not really a bridge like on games where it's on the top). This is possibly because the Keep is meant to be isolated.
When you are in the Keep, you see the Clock Tower, which makes sense, I guess. Interestingly enough, in the background of the Keep, the clock tower has numerous connecting bridges to the tower next to it, even though there's no tower in the map.
Ecclesia: The Mechanical Tower is on the right side, like the Tower of Death and Rondo/CV3/etc. clock tower. There are no real connector hallways from the top of the tower to the Keep, though halfway up the tower there is one lone hallway that goes left to the center of the castle, the Forsaken Cloister. It's too low to be a bridge though, and certainly wouldn't show up in view from the Keep. What does show up, though, and very large and imposing, is the Mechanical Tower in the background, a large square giant tower.
Lament:

?
Curse:

?
OoS: No tower
LoS: There is a clock tower, and it is in the castle, and once you get past it you reach the keep, sort of.