There is an imposing Senatorial building (The European Council) and a European Parliament. Brussels has its own K-street, Rue de la Loi (or more commonly known as Arts/Loi). Yet there is one aspect Brussels is lacking in the European Quarter: Grandiose Monuments.
Although the EU institutions stand proud over the Brussels Capital Region, the European Institutions have an ambiguous, in a way bi-curious role.
On one hand, the European Institutions are considered part of the international institutions, entities without sovereignty, while on a more practical sense, it is clear that the European Commission, and the institutions as a whole, are slowly accumulating more and more power. And maybe this is why the Brussels Capital Region doesn't flaunt the immense power it wields through symbols of power.
The European Institutions bring immense negotiation power for trade deals, leverage with multinational corporations, and competitive advantages when it comes to market access, but also huge political tensions, especially when it comes to migration.
This tension is visible throughout the history of EU politics - every decision is made conscious of the different perceptions. Landmarks, laws (which are called directives or regulations - likely to not undermine national authority) and even the architecture of EU institutions are built with this in mind.
For example, in Washington, or even Belgium's Brussels, when it comes to national institutions such as the Royal Palace or Cinquantenaire Park, there is always direct intent to show national power and authority through culture.
The European institutions don't have a diplomatic service; they have the European External Action Service. The EU doesn't have a direct way to issue bonds, but they have various mechanisms that look almost identical.
For instance, the European Parliament has its hidden staircase of further union. In contrast with the 365 steps to Capitol Hill in the United States, or the stairs to Rome's Campidoglio, Brussels has a more low-key symbolic staircase that goes down towards the hemicycle. It's not in the fancy styles typical of Antwerp or other Belgian cities—no art nouveau and fancy frills—only a hidden stairway that one has to descend in a 2-2 marching step.
Though never confirmed, I like to imagine that these stairs under the European Parliament symbolize the inevitability of further union. And much like the crisis-driven steps that bring Belgium closer and closer to the heart of Europe, the union is also a goal you can see while walking down the stairs.
Something I find particularly tasteful is how, unlike other architecture and monuments which represent power, these stairs put the citizen on the high ground walking towards the center of democratic power (the plenary).
Colloquially anglicized as Plux, or "pluxing" when you go out with friends, the curious effect the EU and NATO have had on Brussels is that it has become the most international city in Europe. Not only that, but Brussels seems to be a huge hub for talent of every kind.
Brussels is a bit of a Mini-Europe; there are sizable diasporas from every nation, and the average inhabitant speaks 3 languages (which in itself is a resource). Though many come to Brussels to get that "Beer stain" on their CV (i.e., experience at an EU institution), I don't see this as a negative factor. With a constant influx of young trainees and foreign professionals, the GDP of Brussels Capital is about 100 billion euros (that's a lot of fries, chocolate, and waffles sold).
Bringing together such talent and cultural diversity is bound to create future wealth, and I believe Brussels will slowly become a center for technological growth—perhaps a side effect of the Europeanization of Brussels.
There is no other place better suited for the European Union's capital. Brussels embodies the spirit of cohesion and diversity that the EU member states bring. At the same time, it also manages to represent the cautious building and negotiation—a key aspect of EU politics.
There is no better place to have the European Parliament, The European Council, and The European Commission. Cities like Leuven, Bruges, or even Ghent (arguably the most beautiful city in Belgium), are just not built for big European institutions and can't represent the Euro-Zone.