I will not even advise any organisation to do such because these days funny things happen, as you do not know the intention of the person you are taking to the lab when such a person is not a staff member or is affiliated with your organisation, and not even a government official on official duty. It is better if the person stays at your office than to let them into your lab. Labs are basically for major work, and most discreet activities of the organisation's production capacity and abilities are kept there, and I do not believe any reasonable organisation would just take or allow any individual to enter without any prior notice or not follow procedures before accessing the lab.