I'm in a city with peculiar buildings (one shaped kind of like stairs) where I'm staying in a relative's appartment, but someone (who is following me?) is able to get ahold of the key to the apartment so they are able to get inside though I don't know where they are. I also end up finding my old credit card after already getting a new one which is highly upsetting
The dream may suggest that you are feeling that someone is trying to intrude and invade your personal space or perhaps trying to take something from you without permission. The peculiar buildings represent your confusion or feeling unsure about your surroundings and the situation at hand. Staying in a relative's apartment may represent seeking comfort or refuge in the familiarity of someone close to you during a challenging time.
The fact that you are unable to find the person who may be following you or able to access the apartment could indicate that you are feeling vulnerable and unsure of whom or what to trust. The discovery of your old credit card could represent a feeling of regret or frustration about past decisions, or a sense of loss of control over your finances. Alternatively, it could symbolize an opportunity for renewal and a fresh start. Overall, the dream may indicate a need for greater security and vigilance in your life, and a desire to regain control over your personal space and belongings.