What does the mean of “at medical facilities”

Question

What does the mean of at?

Japan's government will quarantine all people arriving from China and South Korea for two weeks at medical facilities as part of its quarantine law.

Answer 1

You should ask What does 'at medical facilities' mean?

It means establishments where medical work is carried out. The travellers will be quarantined in hospitals or clinics, not in hotels or at home.