We only had 2 hours, which was only enough to cover off the first building. As others have mentioned, reservations are required. If you are a foreigner, don't waste your time with the WeChat QR code (we couldn't get to work anywhere). Go to the small office on the right of the entry hall and get an entry pass by showing your passports and filling in a sign-in sheet. We rented the audio guide and the English commentary was clear. We did not realise how large this museum is and would definitely recommend a whole day or spreading a visit over two half days.

Very good collection of artefacts. The audio guide for RMB20 is in English and was well worth it as not many displays have written information in English. As a foreigner, go to the ticket office on the right hand side after entering the main building where they will check your passport and give you a free ticket. You should try to register beforehand but someone at the office helped me do this. Only downside of the museum was that it was extremely crowded, be prepared to be pushed into when looking at the exhibits. Definitely worth the visit despite how busy it was!

Lots of interesting artefacts and by far the most accessible for English speakers of all the Nanjing attractions I went to. It was sometimes hard to follow the chronology of the history on display though. Multiple buildings mean you can easily spend 3+ hours here. Is very crowded though.