If you dream of a fort, it generally signifies protection and safety. It is telling you that you are protected. You may have built up defenses to keep people out or to keep your emotions in check. If this is the case, then the dream could be about erecting barriers to protect yourself from emotional pain, rejection or judgement.
For example, if someone has just moved into a new neighborhood and they are getting to know the people there, they might dream of a fort. That would signify their fear of the people in the neighborhood that they don’t know yet.
The fort could also represent an enemy encampment or settlement. If someone is camping alone, they might dream of an encampment. This means that they feel out of place and threatened or lonely during their time alone in nature.