Why the para nasal sinuses are assembled around your nose?

They have two main functions: 1) As in all sinuses, they give size without added weight and 2) They give depth to the voice.

You have the para nasal sinuses, assembled around your nose. You have maxillary sinuses, frontal sinuses, ethmoid sinuses and sphenoid sinuses around your nose. These sinuses make the area around your nose, very light in weight. The diagonally opposite part of the skull is thick and heavy. That is occipital bone for example! This has an evolutionary advantage to human being. After deep inspiration, you can float in the water, without any efforts. So these para nasal sinuses has helped you to keep your nose out of water. The opposite thick part of the skull help you in this endeavour. You can very easily understand the importance of your nose in water verses your nose out of water. That is the reason, why the para nasal sinuses are assembled around your nose. All the other advantages are accessory, probably.