What are some ways alumni can visit their old high school while still maintaining building security?

The high school in question recently closed the campus off at all times (even after school) and only students, staff and visitors with appointments can gain entry, unless a public event restricted to a specific space, ie. gym, auditorium. An appointment requires photo ID (no problem), the appointment itself (useless after school due to many teachers departing, useless to older alumni don t know any of current staff), and then also need to be escorted in building during time there (same issue as above, some may want to just roam around for few mins and leave)

I may be answering my own question but does anyone else have any ideas? There can maybe be alumni events, but maybe a visitation system after school where alumni apply for pre-screened access beforehand and pick a day they want to come, they will scan a QR code on their phone at the school security desk confirming their appointment, will then be checked with metal detector and have (small bags) searched if they have any. They can only spend certain time inside and must sign back out again.(appointments put on admin & security, not individual teachers/staff, no escort needed because only pre-vetted and searched individuals will be inside) I may be answering my own question but does anyone else have any ideas?