(4) Any building and its equipment in the course of construction on or after the first Monday of March, 1954, together with the land on which it is located as may be required for the use and occupation of the building when the building and equipment is being constructed for the sole purpose of being leased to government to lessen its burden. "Uniquely of a governmental character" means the property, except hospitals, water systems, waste water facilities, golf courses, and toll bridges, is not intended to produce income or revenue in the form of rents or admission, user or service fees, or charges.