We had a wonderful stay in Brussels and the location of Florence's place was ideal for the event we were attending at the Bozar. It is 5 minutes walk from the Gare Central, but we arrived on the Eurostar at Gare Midi, where we caught a bus to Royale/ Koning, the bus stop is less than a minutes walk from the apartment. We were surprised and delighted when we arrived as the apartment was much bigger than we expected from the photos. There is a small (very small) elevator to the 3rd floor, then narrow stairs to the 4th floor flat, which could be a problem if you have a lot of large luggage. We managed okay as we only had one large bag between us. As you come out of the street door there is a reasonable Italian restaurant pizza/pasta which also has a bar with a good selection of Belgium beers (it almost became a ritual with us when returning to the flat to stop at the tables in the street outside the cafe and have a beer before going in our door). If you turn to the right as you come out there's a rather expensive cocktail bar if you want to treat yourself to something fancy. However the apartment was amazingly quiet, with not much in the way of street noise.
A place to leave our luggage in the building was an added bonus as our train was not until the evening.