Cave 
To dream that you are walking in a dark cave represents your subconscious mind or the attempt to seek out shelter. It signifies that you are enduring bad fortune or an argument that wasn't foreseen.
Grotto
To dream about a grotto represents relationships that are unfinished. In addition, in can represent a rotation of friends that are not reliable.
Hollow
To dream of something hollow refers to the womb and nurturing feelings. Hollow things can also represent a hidden secret or an empty box. Sometimes, it's a mere manifestation of your current emotions, perhaps that of unimportance, negligence, and emptiness. You need to understand that no one can fill that hollowness but yourself. Appreciate yourself and acknowledge what you have in life.
Collapse
To dream that you collapse implies that you are setting too high standards and expectations for yourself. You need to reevaluate your objectives to make sure that they are still valid. Perhaps you have lost confidence in your choices, opinions, and beliefs. .
Apartment
To dream about an apartment represents your current position of monetary well-being. To dream of a large, lavish apartment implies that an aspect of your life will substantially increase in value. To dream of a shabby and dark apartment signifies that you may experience a run of bad luck or may lose something of great importance and value.
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