Call of Duty troopers have explored everywhere from the muddy, bloody trenches of World War II to the depths of space in a high-tech near future.
The long-running shooter series’ battlefields and multiplayer arenas are well-charted territories, with hordes of dedicated players making it their personal mission to map out every square inch of them, yet relatively few stumble upon all of their secrets.
Indeed, CoD developers love to hide Easter eggs around the story missions, rewarding intrepid fans who venture off the beaten track, and the best multiplayer maps are packed with concealed nooks, crannies and vantage points ideal for picking off noobs unseen.
Uncovering these secrets has been a CoD tradition since the first instalment charged onto the scene, all guns blazing, way back in 2003.
Even the most decorated CoD veterans are unlikely to have uncovered every Easter egg, secret location, and hidden sniping spot that these games have to offer.
However, learning about those which passed under the radar the first time around will no doubt be all the incentive they need to dust off their copies of the older games, reload their rifles, grab a handful of grenades, and head back to the battlefields of old.
With that said, here are the 15 Hidden Areas You Completely Missed In Call Of Duty.
15 Crossfire’s Highrise Rooftop (Call of Duty 4: Modern Warfare)
Call of Duty 4: Modern Warfare has always been a favorite among deathmatch addicts, and with some of the best multiplayer maps the series has ever featured on its books, it's easy to see why.
The secret to kill streak success is finding those sweet spots on the maps, hiding places where you can lay low and pick off the other players undetected.
There's one of these spots on the "Crossfire" map, which fans can now enjoy in 1080p thanks to the release of the Remastered edition, but not everyone has discovered it since it's tricky to reach.
Make your way to the three-walled building with the chair and cooker on the first floor. Using either of those household items as a launchpad, it's possible to leap up to the next level of the highrise, and several jumps later, you'll be at the summit.
This is a great vantage point for sniping. Camp up, take aim, and watch those kill streaks build up.
14 Nacht Der Untoten (Call of Duty: Black Ops II)
Nacht der Untoten, which translates from German as night of the undead, is a classic map from Call of Duty: World at War's Zombies mode, but the building it is set in also made a secret cameo appearance in Black Ops II.
To find this blast from CoD's past, fire up the Zombies map Green Run (which is part of TranZit) and hop off the bus between the farm and the power station. Make your way across the cornfield and you'll find some familiar ruins on the horizon.
Those well versed in their CoD history will recognise them as Nacht der Untoten, or at least what's left of it by this point on the Zombies timeline. Not all of the building is accessible this time. The help room is blocked by debris and the stairs have collapsed, but the starting room can be freely explored.
13 The German Dance Party (Call of Duty: Finest Hour)
Call of Duty: Finest Hour is chock-full of Easter eggs, and while most of them are delicious, the good news is that none of them are as fattening as their chocolate-covered counterparts.
There's another secret room that you should investigate on the "Underground Passage" mission, and this one can be accessed via the hole in the wall near the first ladder. This leads to a tunnel through which you can access the basement of the house.
There are a few boards blocking the entrance, but that's nothing that a couple of grenades won't change. On the other side of the barrier is a full-blown German dance party and you've just exploded your way onto the guest list.
Whether you join in with the festivities or bring them to an end in a hail of bullets is entirely your decision.
12 Nuketown’s Hidden Room (Call of Duty: Black Ops)
The fan-favorite Call of Duty: Black Ops multiplayer map "Nuketown" has a well-hidden room that just so happens to be ideal for snipers to rack up the kind of kill count that Marvel Comics' antihero The Punisher would be proud of.
To find it, head over to the yellow house with the broken windows and take the stairs to the top floor. From there, jump until you're standing on the doorframe between the bedroom and the room with the mannequin inside.
Now turn left and so you're facing the wall with the cabinets and walk through the gap in the wall until you reach a chamber with another mannequin on display. This is the perfect vantage point for attacking other players from the shadows.
11 The Groesten Haus Mystery Box Room (Call Of Duty: WWII)
Easter eggs and secrets are everywhere in the "Zombies" mode of any Call of Duty game, and in the recent WWII instalment, there's even one in the prologue mission.
The tiny Groesten Haus map is a tutorial stage which gives players a crash course in the art of surviving an undead onslaught, but there's more to it than meets the eye.
On the upstairs level of the house is a secret room, and unlocking it is a simple matter of shooting 10 lanterns. Inside the room is a mystery box offering a random weapon in exchange for 1,000 Jolts, a small price to pay for extra firepower when an army of reanimated corpses is breathing down your neck.
Although Groesten Haus is designed to teach players a few quick lessons, finding the mystery box makes it possible to survive an extended stay at the zombie-infested homestead.
10 The UFO House (Call of Duty: Finest Hour)
Extraterrestrial-themed Easter eggs have cropped up in the Call of Duty series on a number of occasions, but not everyone had a close encounter with this one in 2004's Finest Hour, mostly because you have to walk through a wall to find it.
On the "Come Out Fighting" level, head to the house with the machine gunner aiming down the hallway, then venture downstairs and outside. Next, hop over the sandbags onto the barbed wire and keep moving until you come across a house. Inside, you'll find a wall that you can pass straight through.
There's a hallway on the other side and at the end of it is a UFO, a flying saucer that the Nazis are in possession of. What the Third Reich is doing with alien technology is a good question, though perhaps a better one to ask is why they didn't use it against their enemies.
9 The Secret RPG's Hiding Spot (Call of Duty: Advanced Warfare)
Not everyone got their mitts on this secret weapon in Call of Duty: Advanced Warfare, since you have to break the game to find it. This is one of those errors you can exploit, but the fruits of this glitch-powered labour were never meant to be harvested.
There's a building way off the beaten track on the "Throttle" level, and it can be found by following the railway track all the way around. Scale the structure ahead and you'll soon find yourself standing on an invisible barrier. This is when the game starts to glitch out.
Keep climbing and eventually the scenery gives way and reveals a floating weapon. This is the WEAPON_RPG-- a gun so rough around the edges that it doesn't even have a proper name.
Firing it yields no gunshot sound effects, though it's an interesting addition to your arsenal as the least technologically advanced blaster in the game.
8 Thor’s Cave (Call of Duty: Black Ops II)
While Marvel Comics and Call of Duty are universes apart, the two properties briefly collided in Black Ops II to bring eagle-eyed fans this cool, superhero-themed Easter egg.
On the "Celerium" mission, shortly after you've flown into the level, eliminate all of the resistance in the area and walk over to the cliffs. Jump down to the lower level and you'll find a dark cave housing an incredible secret.
There in the cavern sits none other than mighty Thor's hammer. Mjolnir would surely be by far the most powerful weapon ever seen in a CoD game -- just think of the chaos you could wreak with that thing -- but sadly it's just for show. Not that protagonist David Mason would be deemed worthy enough to wield it anyway.
7 The Giant Red Apple (Call Of Duty: Finest Hour)
Easter eggs hunters have uncovered all kinds of strange stuff in the Call of Duty series over the years, and giant fruit has to be up there with some of the most bizarre discoveries. This is another secret which dates all the way back to Finest Hour, and it's well hidden.
Instead of following the beaten path, head in the opposite direction from the starter area and look out for a snowbank on the right. There you'll find a dead tree positioned further back than the surrounding foliage, and heading towards it will see you ascend a slope.
Next, turn left and follow the mountain path around and marvel at the gigantic apple you'll see before you. This oversized piece of fruit serves no purpose, but somebody should probably tip Strongbow off about its existence.
6 Sainte Marie Du Mont’s Secret Sniping Spot (Call of Duty: WWII)
The best Call of Duty multiplayer maestros bend the rules by manipulating glitches to reach secret parts of the maps, areas the developers may or may not have intended them to access. Some might call this cheating, while others have only admiration for the creative players who brought these exploitable bugs to light.
Those who are totally okay with this practice can find the best sniping spot in Call of Duty: WWII's popular Sainte Marie Du Mont arena by jumping on the hood of the golden car which lies on the Axis side of the map.
From there, look out for a sandbag ledge to the right and use it as a foothold in your climb to the top of the building in the Axis Spawn, a vantage point with views spanning from one end of the map to the other.
5 The Ghostly Room (Call Of Duty: Finest Hour)
A creepy experience awaits anyone with the guts to uncover this Easter egg in Call Of Duty: Finest Hour. The "Ghostly Room" is a well-kept secret on the "Underground Passage" mission and it can be accessed via the spiral staircase at the beginning of the stage.
To the right of the room full of German soldiers lies a passage leading to a large tunnel. You'll see what appears to be an unopenable door with a medipacks beside it in front of you.
Toss two grenades at the door and then hit the action button in front of it to gain access to the narrow tunnel on the other side. Those who dare venture further will find themselves in a haunted room.
Who needs the horrors of war when you've got Easter eggs that go bump in the night?
4 The MC Hammer Area (Call of Duty: Ghosts)
You may have walked past this secret location on Call of Duty: Ghosts multiplayer map "Freight" on countless occasions (assuming you're one of the few who got any longevity out of Ghosts' multiplayer) without realizing its significance.
Following the area's wall of shipping containers will lead you to a tucked-away location where three objects have been laid out side by side, seemingly at random. There's a stop sign, a hammer, and a clock.
There is, in fact, nothing random about the placement of these items. It's a subtle reference to one of the most '90s rap songs ever recorded: MC Hammer's "U Can't Touch This".
Musical Easter eggs can be found throughout the CoD franchise, but this doozy from Infinity Ward is the most nuanced of them all.
3 The Village Church Roof (Call of Duty: Modern Warfare 3)
Like most entries in the Call of Duty series, Modern Warfare 3 has its fair share of sniping spots-- perches you can position yourself on to rain down death from above.
One of the most effective can be found on the "Village" map by making your way to the church. Stand beside the podium and hop onto the tall box and walk towards the front of the building. From there, you can run, jump, and melee to the next floor.
Lather, rinse, and repeat, and you'll find yourself on the fourth floor, and from there it's possible to reach the roof. Whether you're playing in multiplayer or survival mode, this is a great place to camp out, and nothing can touch you up there, not even helicopters. (A classic song by The Drifters springs to mind.)
2 The Trophy Case (Call Of Duty: Ghosts)
The trophy case found in the offices on Call of Duty: Ghosts' "Federation Day" mission is a mini emporium of cool Easter eggs, and you probably walked right past it on your most recent playthrough.
While making your way towards the next objective as you escape from the skyscraper via the elevator, stop, and take a look around the offices. One of the trophy cases is a fanboy's dream, proudly displaying references to Doctor Who and The Legend of Zelda.
This cabinet plays host to a trophy shaped like a police box with the words "Award for largest interior and smallest exterior" inscribed on it, a clear reference to the Doctor.
The other is shaped like a Zelda rupee and is etched with the words "Award for most bushes cut and pots smashed." There's also a nod to the Mayan doomsday prophesy, which thankfully never came true in 2012 (apart from in a terrible movie), in there.
1 The ‘Lost’ Hatch (Call of Duty: Modern Warfare 3)
Lost had wrapped up its final season by the time Call of Duty: Modern Warfare 3 hit shelves in 2011, but the game's development team did its bit to keep the mind-bending show's legacy alive with a subtle reference to it on one of the multiplayer maps.
The famous hatch from the ABC drama can be found in the corner of the "Village" level. Head past the church and continue onwards to the far right corner of the stage. You'll find a red and brown house, and behind it is the hatch from Lost, situated on the wrong side of an out-of-bounds fence.
Rather annoyingly, you can't actually walk up to the replica television prop, but you can take a good look at it in spectator mode. There's no doubt that this is the hatch from the show. It even has Hurley’s numbers -- 4, 8, 15, 16, 23 and 42 -- etched on the front.
Can you think of any other hidden locations in Call of Duty that fans need to know about? Let us know in the comments!