Any provision contained in any contract relating to the construction, alteration, repair or maintenance of a building, structure or appurtenance thereto, including moving, demolition and excavation connected therewith, or any provision contained in any contract relating to the construction of projects other than buildings by which the contractor performing such work purports to indemnify or hold harmless another party to the contract against liability for damage arising out of bodily injury to persons or damage to property suffered in the course of performance of the contract, caused by or resulting solely from the negligence of such other party or his agents or employees, is against public policy and is void and unenforceable. This section applies to such contracts between contractors and any public body, as defined in § 2.2-4301. This section shall not affect the validity of any insurance contract, workers’ compensation, or any agreement issued by an admitted insurer. The provisions of this section shall not apply to any provision of any contract entered into prior to July 1, 1973.