The two main designers of a structure are the architect and the civil engineer; both professions being integral to the structure's execution and construction. Their responsibilities often overlap.
The architect will design a space to meet the client's needs, and will come up with blueprints for both the inside and outside of a building. Because the architect is ultimately responsible that the building is safe for its occupants, he or she will work closely with a civil engineer to ensure the structure meets all the appropriate building codes.
The civil engineer can also advise and/or select the appropriate structural materials, and help with specifying the plumbing, electrical, heating, air conditioning, and ventilation systems that will be needed.