In most cases you will receive written notice that condemnation proceedings are being considered even before the actual condemnation proceedings begin. You may even be extended an offer of compensation prior to the filing of the condemnation proceedings. When the condemnation proceeding is filed in court, you will most likely be served by mail or by a deputy sheriff with a copy of the proceedings and with a summons requiring you to file an answer within a certain period of time if you wish to contest the condemnation.
In some instances a condemning agency takes property before filing proper legal proceedings. In that situation, the landowner can usually file a action for inverse condemnation seeking damages for the property taken. There are statutes of limitation that apply and when you learn that your property has been taken you should consult a lawyer immediately to avoid the running of the statute of limitations and your claim for compensation being barred.