How to create a different reality tethered to present time? Kind of like Gotham? I keep envisioning this contempary romantic suspense trilogy in which the gulf between the rich and the poor has widened to the point of incredible extremes with the villian being more a corporation type mentality than one person. I don't want it to have a sci-fi feel to it. The idea is so huge I keep shoving it away, but it keeps coming back! Anyhoo, that's my question? Which you are at liberty to ignore if it makes no sense.
This is such a fabulous puzzle, and a really intriguing piece of world-building. Small towns on the middle of the prairies or remote mountain communities are one thing to create, but creating a metropolis grounded in the present day can have massive repercussions on the world at large, and many areas where a reader might go, "Wait a minute..." and then get knocked right out of the whole thing.
Karyn has already started us off on excellent footing by mentioning Gotham City (home of Batman, for the non-comic-oriented). Comics are a perfect example of this sort of world-building, and an excellent case study to see what works and what doesn't.
I'll preface this now by saying it will get long, but it's a complex issue and deserves due attention. Post will be cut on the front page for space-saving, so click the link at the bottom to read the whole thing.
The Alternate Reality
What you're essentially dealing with here is an alternate present, or near-present, depending how you want to approach things. You're telling your readers "This is the now. All your standard assumptions are fine as far as fashion, technology, culture, unless I call attention to something that says otherwise." Your city (I'm assuming city scale since you mentioned Gotham, but it could go larger) needs to fit in with the rest of the world, and any changes you may make, or large influential things you do need to gel with what we the readers know to be true.
Where is this fictional city set? Will you be referencing North American culture, European culture, Asian culture? (For simplicity's sake I'll run with North America for examples) Do you have any particular cities in mind for reference? How closely it resembles something familiar can determine how easily your readers will believe it exists as part of the real world. For example, Batman's city was originally Manhattan, but was changed to Gotham. Comic writers didn't want residents of any particular city (most obviously New York) to identify with it. This gives them license to change things according to story without anyone saying, "But wait, there's no area like that." If, however, the cultures and customs in Gotham seemed wildly different from North American cultures and customs, readers would wonder why the heck no one else in the States or Canada acted that way.
Know your world at large so your fictional city rings true within it...but of course don't let that stop you from creative world-building inside the city limits.
'...but with Zombies'
The other thing to consider in establishing your fictional reality is the prospect of drawing a sharper line between the reality we know and the reality you're presenting. This is essentially how comics at large function. While Batman may reside in fictional Gotham City, Spider-Man lives in New York City. The X-Men are also based in New York State. X-Men is basically pseudo-modern society where mutant evolution has thrown a whole new element into the system. It's a 'What-If' scenario, taking Western culture and dealing with a new wildcard. Superhero comics in general essentially function under this, in that they're worlds with superheroes. It's obviously not our present day society, but we wouldn't call it futuristic or anything.
You could build your world off something as simple as "present day society if the stock market hadn't crashed" or "if the Great Depression had gone on another twenty years" for example, and follow your hypothesis through from there. The catch, of course, is you really need to do your homework and make your idea work. Small changes with large ripples are often easiest to handle (Pride and Prejudice, but with zombies).
Blurring the Edges
Whichever way you go about it, you need to ease your fictional city into the real world without disturbing everyday life too much. Your metropolis needs to coexist with all the other ones out there, without either seeming to erase one or muscle in on it. Think of your city like a germ. No really, run with me here. You place this foreign organism in the flesh of an existing world, the last thing you want to do is call attention to it! All the other pieces would turn on it and try to drive it out. (Or if you've seen Inception, think of it like meddling too large scale in someone else's dream. Unhappy people sensing tampering will mob your poor city and destroy the happy dream world of your book.)
Instead don't call attention to your city. Don't tell us how many hours it takes to reach New York, or Toronto, by car. An overnight flight to London won't change much if your city is 'somewhere' in North America, but giving us something tangible to locate it with will start to throw up alerts that something's amiss. Anyone who lives near the area your referencing will rebel at those false details. Instead stay vague, blur the edges of your city so it looks like it fits in. Give us a climate (East coast, west coast? Northern or southern?), a sense of broad-scale place and we can do the rest.
The Dark Knight (2008) is a great example of this. Almost the entire action takes place within the boundaries of Gotham City. The only scene that breaks away from the iconic city takes place in Hong Kong, incredibly far removed both geographically and culturally. No one drives out of Gotham and winds up elsewhere -- in fact, no one gets out at all. Based on Manhattan, Gotham's main escape routes are over bridges, through tunnels, or by ferry, none of which allow for one to simply wander out of the city. Your fictional city is the key set piece in your novel, so give your readers what they came to see. No one wants to see day trips to Calgary or a weekend at some generic lake when we could explore the city you built from the ground for us to lose ourselves in. Keep us from fitting your puzzle piece directly into the overall picture, and we can let it adapt based on our individual perceptions.
Mise en Scene
All of this helps you build a city and ease it into an existing world without too much friction, to prevent readers from having that dreaded, "Hey, wait a minute...." moment. None of that, however, focuses on the actual building of your city. As I've talked before about world-building, the most important thing you can do to bring your world to life is make it feel realistic. Things like a unifying theme, as we've discussed in the past, can help give your city an identity readers can latch on to. For something like this, though, I believe the most powerful thing you can give a city is mood.
Mise en scene is a film and theatre term, essentially referring to the way everything on the stage, from lighting to props to sets, costumes, actors -- and in film, cinematography, score, even scene changes -- help to create an overall tone or mood. The Underworld movie trilogy is a great example of this. Every scene, every shot, offers the same stark, shadowed tones which bring a Gothic touch to the movie. Beyond that though, nearly every shot has been lit, set, and altered in post-production with a unifying blue tone. You'll find the same in Batman films (and comics, of course). Look at both of Tim Burton's Batman films, with their iconic style, drab lighting, and mood of something over the top gone rotten over time. Christopher Nolan's new films are also unified in palette and tone. Even outside Gotham (again, going back to the Hong Kong scene), we have the same cool blue-grey lighting.
Find something iconic and evocative to latch on to in your city and bring a touch of it into every facet. You've mentioned a wide gulf between the rich and the poor, which makes me think of great squalor and disrepair contrasted with grand, sleek, elite places. Something in tone, mood, colour, etc can unite the two of them, for example by making both seem rough and dangerous, or 'rotten-ripe' but in different ways. Even something small -- in my WIP's major city I pull on rain and lanterns to create ambiance, regardless of a district's wealth.
Having a unified atmosphere for your city helps make it feel unique and independent. If it's a little of everything, then it could become a "Capital City" everyman, and then it may begin to represent your source material more than its own identity. In my opinion, I've always found it pointless that Superman lived in and protected the city of Metropolis. It was big and important, but generic, so I figured they might as well have just stuck him in New York like Marvel did for Spider-man. (Although fun fact, the Metropolis skyline was originally modeled after Toronto, where co-creator Joe Shuster was born).
The other big thing about creating an ambiance for your city, it makes your setting come to life. The best, most memorable places in fiction are the ones where the cities, environments, or buildings felt like characters in their own right. Think of Harry Potter's Hogwarts, The Shire of Lord of the Rings, and of course Batman's Gotham City. Each evokes a specific mood and tone, an expectation of what we'll find in it. There are no quaint, idyllic suburbs in Gotham City; we know on instinct they would be wrong in that setting. We know what these settings will hold just as we know when a character's actions ring true and when they're off. This sort of unity also makes us want to explore and learn more. The best characters make us long to come back and spend more time with them. The best settings should make us long to get in and explore for ourselves.
The Details: Commerce, Tech, Influence
Finally we come to the details, the little things you can take great liberties on, or which can disrupt the unity of your fictional city. You've given a specific scenario, looking at a city with a massive wealth gap, so I'll just highlight a few key things to think about.
Money: How did this gap emerge? How long has it been this way? Why won't it change? Why isn't the rest of the country in a similar state? Don't let these questions become road blocks for you. Just take a look at living examples and the cultural ramifications behind them. Plenty of things can go into neglecting a large chunk of a population, and unfortunately there are many viable examples in present day to draw from. You just need to know whether this is an issue that divides race or ethnicity, for example, or if it cuts across all sections for some other reason. Give us enough to feel the explanation holds up, and we'll believe you know the rest even if you don't.
Technology: With the wealthy, and with corporations, can come the fastest and newest of modern technology -- things the real world may or may not have. How much this plays a part in your novel depends on the story itself. As a rule of thumb though, the less you're emphasizing the alternate reality, the less you want your tech to differentiate itself from contemporary standards. If your characters have something the real world doesn't, why aren't they marketing it and selling it to real cities around the world? The super-elite will always have access to things that aren't mainstream and familiar, however, and there can be some level of forgiveness if it's necessary. Iron Man is a good example here (I'm looking at the movies, since they blend nicely into 'modern' society). The standard comforts don't strain modern parallels too much, except a genius billionaire like Tony Stark is bound to have some nifty gadgets and personal inventions others might not.
Influence: The other potential red flag I'd see coming up here is your corporate entity. How big are they? How influential? What do they do? Do their actions have effects beyond your fictional city? You need to be able to justify their wealth and influence without completely toppling the city's place in a realistic world (or you could do a "but with zombies" approach and make something they do the big difference between real world and your world). Anything corporate implies a reach beyond a single city. Think about their role in a novel, why are they antagonistic? What is the conflict? I'm guessing they have a part to play in the economy gulf, what is their reason for it? Depending on your answers, something innocuous may give them the clout you want without the questions (such as steel, oil, food, or electronics -- the last of which does potentially create tech issues). If the corporate machine does something more particular or unique, you need to be able to answer why it hasn't effected economic standings outside of the city, or altered my life as the reader.
Again, we have Batman as an example with Wayne Enterprises which has an incredible amount of influence in a huge amount of things, and dates back to the 17th century, founded by merchant ancestors of the Wayne family. The length of time alone justifies huge wealth and influence. The key thing is to ensure your corporate entity isn't just a faceless antagonist for making things hard. I cringe at economics, but plenty of other readers will know if there's a gaping hole in the corporate business model.
So Karyn, I hope this has been helpful to give you a good starting point with this concept. Cities like this really intrigue me, and I would love to see what you come up with. If you have any more questions or would like to delve into more specifics, this thread is all yours, and I will do my level best to delve into anything you like.
For everyone else, if you have a question or a problem you'd like to throw out there, please feel free to leave a comment and I will give it my best in a future post!