There are several bus companies that run hop on hop off services in Hanoi. We had picked out Bon Bon, which is a new company that had excellent ratings. Unfortunately, we could not find a bus stop convenient to where we were staying. I contacted them on Facebook for the closest stop and was given an address about 1/2 mile from our hotel. We walked there but found that it was a bank (they had told me it was a café). Hmmm. We decided that if it was going to be that difficult to find where to catch the bus that we needed to find a different bus company.
Instead, we used Hanoi Hop On Hop Off Bus Tours (https://www.hop-on-hop-off-bus.com/hanoi-bus-tours) which had a convenient stop a few blocks from the Oriental Suites, right by Hoan Kiem Lake. Our primary goals were to get to the Ho Chi Minh Mausoleum and to reorient ourselves to Hanoi (we had visited a year ago).
Clayton was interested in visiting the Vietnam Military History Museum, so we hopped off there (stop #3 on the route). We found it well worth a visit. Here is a link to pictures and a summary of our time spent there: Vietnam Military History Museum
Next up was the stop for Ho Chi Minh Mausoleum. Be ready for a long walk to get to the entrance from the bus stop if you ride the HOHO. Click here to read about the complete experience: Ho Chi Minh Mausoleum
We decided to ride the rest of the route without getting off the bus, and to return to any place of interest on another day. It was a good decision to ride the bus because the city is spread out enough that it would be difficult to walk to many of the main tourist attractions. Though we had visited here before, it was helpful to have a refresher regarding how the city was laid out. We decided to visit the Temple of Literature and Women’s Museum. If you have not been to Hanoi before, the Hoa Lo Prison is well worth a visit.