For your first visit you need about a day and a half. Hardly any attraction rises to must-see status.
Distances are walkable in the city center, but some attractions are better reached by trams.
Love its majestic main square, Grand Place.
Don’t miss: walking through Ilot Sacré and going to one of the eateries located there for a dinner; sampling waffles or frites (not simultaneously) from any vending hole-in-the-wall.
Worthy attractions: Cathédrale Sts Michel et Gudule; Église St-Nicolas; Horta Museum and Maison d’Autrique, two creations of the local Art Nouveau genius; The Atomium; Mini-Europe; Toy Museum.
Left for another visit: Musées Royaux des Beaux-Arts; Museum of Cocoa and Chocolate; Museum of Beer.
Wise to skip: Ok, you can’t really really skip it, but Manneken-Pis is the most disappointing famous sight in the world.
Last visit: April 2015; a Mini-Europe-only stops in April 2008 (brief) and May 2009 (detailed).

Brussels does not really compare overall with grand European capitals such as Rome or Paris. Unless your main interests are culinary (see below), or you feel obligated to visit the Royal Art Gallery and other hardly essential museums, you only need about a day and a half in order to see the city. But it still offers some interesting sights to the discerning traveller.
Things to See
Grand Place ♥♥♥ (in French), or Grote Markt (in Flemish), is a fantastic central town square, surrounded on all sides by 17-century architectural gems. Hotel de Ville is positively magnificent, but other buildings each hold their own. As architecturally-stunning grand public squares go, Grand Place is definitely up there with Piazza San Marco in Venice or Piazza del Campo in Siena.
There are a couple of museums in the square buildings, which we skipped.
The rest of the Lower City is made up largely of aesthetically-pleasing narrow streets and small squares, providing enjoyable walking environment. Larger squares have many attractive buildings. Place de Brouckere ♥, which we only glanced at for a few minutes, bears ambient resemblance to Puerta del Sol in Madrid.
Manneken-Pis (the Peeing Boy) is probably not worth the time spent on viewing it, but in reality, it is too famous to be consciously avoided. And, after all, it is only a couple of blocks away from Grand Place. It is a small sculpture/fountain at an otherwise unremarkable corner. Fontana de Trevi it is not.
Cathedrale Sts Michel et Gudule ♥ bears uncanny resemblance to Notre-Dame de Paris from the outside. It is not very remarkable on the inside, except for brilliant stained-glass windows. The cathedral has been fully restored and cleaned only 15 years ago, and the mosaics are a pleasure to behold.
Eglise St-Nicolas ♥ is the only other church that we visited. Impressive Gothic-style exterior hides no less impressive interior, especially beautiful gilded gates leading to the choir.
Parc du Bruxelles ♥ is an amiable green space in between blocks of monumental architecture. There is a children playground and a small performance stage within its confines, but mostly it’s alleys, trees, benches, sculptures and fountains.
Brussels was home to one of the titans of Art Nouveau, Victor Horta. There are several buildings designed by Horta that are used for various purposes, but also several houses that are dedicated to the architect himself. Horta Museum ♥ is the family house built in 1901, with splendid living space and arresting accents. Open Tue-Sun, 2-5:30pm. Maison d’Autrique ♥ is a house Horta designed for a wealthy patron in 1890-s, which displays some of the attributes of late 19th century living, in addition to the Art Nouveau design. Open Wed-Sun, 12noon-6pm.
It should be duly noted that Horta is no Gaudí.
The Atomium ♥ is the gigantic model of the atom, consisting of nine metallic squares connected by stairs and escalators. Some spheres contain middling expositions, while the top one provides panoramic views over the city. The Atomium is located some distance from the city center, but is easily reachable by either tram or the Metro.
Mini-Europe ♥♥♥, located in Bruparck by the Automium, consists of a couple of acres of 1:25 scale models of European Union members’ landmarks. The entrance fee is stinging, €47 for a family of four, but the place is altogether fascinating. Children absolutely love recognizing the places that they have been to. Many exhibits have moving components that are operated by pressing buttons – another favorite of the kids; for instance, the model of Mt Vesuvuis imitates its eruption, the model of Finnish Baths has people plunging into frigid waters, etc. There are several interesting interactive activities in the pavilion that concludes the route. Closed mid-January through mid-March.
Calling the Toy Museum ♥ a museum is a bit of a stretch. It is a three-story house, chock-full with different types of toys from all over the world. Toy soldiers, dolls and doll carriages, model cars, ships and trains, puppets, et cetera, et cetera… Adults will feel as if they are transported back in time, kids will simply enjoy playing around (yes, you can touch and even play with a lot of stuff). Closed Mondays.
The Comic Strip Museum (Centre Belge de la Bande Dessinee) is devoted to the medium which Belgium is considered a capital of. Unfortunately, it is not something that we are very familiar with or have much affinity for. Also, while there are some English signs and even sporadic English-language exhibits, majority of displays are in French, which further diminishes already little enjoyment. Closed Mondays.
Other places that we skipped on this trip: Musees Royaux des Beaux-Arts (boasting one of the best collection of Flemish masters in the world), Museum of Cocoa and Chocolate, Museum of Beer.
Transportation
Brussels Metro and Tram system is quite convenient for travel around the city and to most attractions.
The efficiency varies, as trains run every few minutes even late at night, whereas trams often have long gaps between them. Metro stations mostly resemble underground pedestrian passages with various shops – not quite attractive, but never overcrowded. Electronic displays show how many stations away the trains are. Some underground stations are integrated between the Metro and the trams.
Tickets need to be stamped upon entering the tram car or the Metro station. It is largely an honor system – we have not encountered a single ticket check, while making over two dozen trips. Single fare is €1.50, but group day ticket (for up to 5 people) costs just €6.70 and allows unlimited trips – unbeatable value.
Places to Eat
All places last visited in early 2007.
Ilot Sacré (sacred islet) ♥♥♥ – several blocks along and around Rue des Bouchers – is a culinary heaven.
Every door is a restaurant, each one offering traditional local dishes with some other regional slant (Italian, Moroccan, Provencal, etc.) Mussels and other seafood dominates, but meats are widely available. The menus and prices are very similar in all establishments, regardless of what they call themselves, and, as far as we can tell, the quality is pretty much on the same level in every one. A la carte selections are rather expensive, but prix-fixe menus are priced very nicely. Each place positions a waiter outside the front door, who extols the virtues of the kitchen to the passerby. It is actually quite hard to walk by without feeling enticed to come in, especially when some sort of a “deal” is thrown in (for instance, a kid eats free).
Prix-fixe menu (starter, entrée, dessert) runs between €12-19.
We had dinners at Le Marrakech ♥♥ (Rue de la Fourche), Le Mouton d’Or ♥♥ (Petite Rue des Bouchers), and Le Vieux Bruxelles ♥♥♥ (Rue des Bouchers). The service was pretty good (its quality diminishes a bit as the place fills up with diners), the food quite excellent.
Several times during our walks, we stopped to sample Belgian waffles. In the tourist zone, there are many “holes in the wall” that vend them. Simple gaufre sucre (a waffle with sugar powder) costs €2. A complex one, with strawberries, whipped cream and chocolate syrup, ran twice as much. Always satisfying if a bit too sweet.
Lodging
As in any large city, the options for a hotel or an apartment are nearly endless on major online platforms. Any location within R20 “ring” will put you within 10 minutes of walking to most of the points of interest. The excellent tram and metro network makes staying somewhere outside of city center workable as well.