Namur is located 60 km south-east of Belgium's capital city, Brussels. It is easily accessible by road (the E411 highway from Brussels), train or boat (the Meuse comes from France and the Samber flow through Namur where they actually meet).
Namur is a smallish city and can easily be discovered on foot. The major areas to visit are the centre of Namur itself, the Citadelle and then the areas along the Meuse and the Sambre.
The Centre of Namur sits between the Namur railway station and the junction of the Meuse and the Sambre. The city is easy and nice to walk around in, as many of the older streets are pedestrian. Saturday morning is market day and most streets in the centre are then occupied by market stalls.
The Citadelle de Namur , a historical fortress surrounded by a large parc is strategically placed on a hill between the Meuse and the Sambre. The Romans built a small city a the foot of the hill early in the first century. Later on, from the 9th century on, the place was gradually fortified to enable it to defend the region, and became a principal residence for the Counts of Namur. From then on the Citadelle has played a role in the history of the country. It is a great place for historical, as well as nature walks. The top of the Citadelle offers a great view of the surrounding areas.
At the foot of the Citadelle, there is a bridge crossing to the other site of the Meuse, where Jambes is located.
Cycling is not too popular with the locals, as the region is fairly hilly. But the city is trying to promote the usage of bikes. Programs such as "li bia velo" (meaning "the nice bike" in Walloon) enable members to rent a bike by picking it up in one station and drop it off at the another. See http://en.libiavelo.be for more informations. There are great walking and/or cycling tours to make along the rivers as both the Sambre and the Meuse have, generally on both sides, paths from where in the past boats used to be pulled. Check Ravel network
Parking in the city can be an issue. The local bus company in Wallonia, the TEC provide "P+R" buses between two car parks in the outer city and the center of the city. The line number is 51 and the two car parks are named "P+R Saint-Nicolas" and "P+R Namur Expo". If you can speak french, you can check it out on the website of the TEC.
Hire a bicycle and cycle up and through the Citadel. Most of the access road is mostly wide and uninteresting, so if you want to walk, make sure to go by the stairs coming from the Grognon (the car park between the Meuse and Sambre rivers next to where they join together). There is also a network of mountain bike itineraries beginning and ending in Namur, but the signage, which was very good at the beginning, with large coloured arrows painted on the road, suddenly vanished without explanation.
A tour company in nearby Dinant (Les Kayaks Bleus, www.lessekayaks.be) organises river kayaking trips. It would probably be possible to paddle downstream all the way to Holland and the North Sea.
One weekend per year, at the end of September or the beginning of October, a big fair called "Fêtes de Wallonies" takes place. It involves drinking a lot of alcohol, mainly the a local type called "Peket". During the afternoon, many concerts, some in Walloons, are given. Avoid staying too late as most activities ends after the evening and then streets consist mostly of a lot of drunk people.
There are public swimming pools in Salzinnes and Jambes.
Namur is often said to be an "open sky" shopping mall. Major shopping streets stretch from the Namur train station to Rue de Fer and Rue de l'Ange where you will find normal fashion outlets like H&M, Newlook,Zara, Kim Pie,Cool Cats, O' Appels, Charles Vogele Switzerland, Esprit, JBC, C& A, Women's secret, ICL Paris IV, Di, Camaieu among others.
The inner city supermarkets are one Match and one (smaller) Spar. Other supermarkets are Carrefour and COlruyt in Jambes and another Colruyt and Delhaize in Salzinnes among others.
Dinant, located about 30 km from Namur upstream, is worth a visit. The place is easily accessible by train and car. If you are up there, do visit de museum of Bouvignes  which focusses on the medieval heritage of the region.
Brussels is a 40 minutes train trip from Namur.
Namur might also be your gateway to the Ardennes and Luxembourg. There is an international train going to Basel, Switzerland and from there to Zurich and Chur.