Chickens could be kept in many urban areas, in some chickens are less welcome. If the intention however is to keep one as a pet, that is already accepted practice. Some are even keeping reptiles for pets but just to be on the safe side, check for local laws and regulations. The local animal control office in your municipality would know how many you can keep and whether that would include a rooster. The main deterrent here is that these birds may fall under noise ordinances and so check out first as it is very easy to be emotionally attached to these birds. In Urban areas that used to be a farming community, the ordinances are more relaxed. Either way, keeping chicken in the city does not require a license.
When the issue of ordinances is out of the way, decide the kind of chicken that you want and for what purpose. If pets are what you want, you would settle well with bantams. Bantams are chicken breeds that are about one fourth of the size of a regular chicken. It is very much like having toy dog breeds. Example of the bantam breeds that are good for pets are the Barred Plymouth Rocks and the Rhode Island Reds as they are mild tempered. If you want a good layer bantam, you would do well with a Cochin. The Buff Orbington on the other hand is a larger bantam breed and is very friendly too. These are only some of the excellent choices. There are many more choices to select on when you surf the net.
You may want your pet chicken to roam around the house, even sleep in the bedroom but the chicken would pretty much prefer its own coop to roost and its own nest box to lay eggs on. You can always build one using the materials that you already have or are readily available at a local farmers market or hardware. When you do, allow a two feet square space for every bantam. The chicken will also need a place to roam; they could be cranky when they do not besides it is good for them. Allow eight square feet for the bird. Chickens are very sociable.
They prefer to huddle together with other chickens. Having that in mind, keep at least two chickens. Likewise, double the spaces allotted to them because even when they are sociable, they could be cranky at times especially when they feel crowded and might start pecking at each other. Remember also that chickens do not need a rooster to produce chicks. Expect then and make provisions that they would multiply soon if you would not need all the eggs they produce.
Remember also that keeping chickens in the city will attract predators. Bantam chickens have no way of defending itself against cats. If you love cats, it would be most likely that you know your cat is not the kind that would attack and could live side by side with a chicken. Rodents however are a different issue. When you build a chicken coop, insure that the coop is very well secured and could never be accessed by these predators.