It is the first thing that puzzles anyone arriving from another capital. There is money, there is demand for offices and there is a city of almost seven hundred thousand people, and yet the skyline stops dead at the same height everywhere.
01 The building that caused the law
In 1894 a twelve-storey apartment block about fifty metres high was completed in a residential neighbourhood. It was called the Cairo, and it was by far the tallest thing built in the city.
The neighbourhood's reaction was immediate and hostile. It was dismissed as its architect's folly, and calls were made for a law limiting the height of residential buildings, on the grounds that it blocked light and outstripped what the city's services could handle.
The law came in 1899 and set three ceilings: ninety feet on residential streets, a hundred and ten on business streets and a hundred and thirty on the widest avenues. The Cairo, already built, remained a permanent exception.
02 The rule still in force
The 1910 version is the one in force today and it changed the criterion: instead of one fixed number for everything, a commercial building's maximum height is the width of the street it fronts, with an absolute ceiling of a hundred and thirty feet, about forty metres. On residential streets the limit is ninety feet.
The consequence is elegant and very visible: the city's height is tied to the width of its streets. Where the plan left a wide avenue, buildings rise; where it left a narrow street, they stay low.
It is worth clearing up a common misunderstanding. Many people believe the rule forbids exceeding the height of the obelisk or the Capitol dome. It does not: the limit is a relationship with the street, and those two structures are simply taller because they are earlier and are not ordinary buildings.
03 What the rule does to the city
The first effect is visual. Downtown, whole blocks are filled with buildings that reach the ceiling and stop flat, producing a continuous surface of cornices at the same level. The city looks trimmed with a ruler.
The second is urbanistic. Since you cannot grow upward, you grow sideways: buildings occupy the whole plot and activity spreads over more ground, which pushes up prices and displaces uses towards the outskirts and neighbouring cities.
The third is the one travellers appreciate. With no towers, the sky is visible from almost any street and the vistas of the 1791 plan still work: from many points you can see the horizon, which is unusual in a capital this size.
04 A rule debated every decade
Every so often a revision is proposed, on the argument that it limits available housing and pushes up land prices. Against that stand those who hold that the low scale is the feature distinguishing this city from any other in the country.
Whatever the outcome, the practical point for a traveller is this: what you are seeing is not an aesthetic accident or a city that stayed small. It is a decision taken more than a century ago and maintained ever since.
And it has a pleasant side effect: residential neighbourhoods keep two- and three-storey rowhouses ten minutes from downtown, something that vanished decades ago in other capitals.
05 What you understand afterwards
With this in mind, the walk changes. You start looking at cornices and checking that they line up, gauging the width of the street and understanding why buildings on one side of an avenue are taller than on the other.
And above all you understand the emptiness. Seeing so much sky in a capital is not urban generosity: it is the result of a neighbourhood argument from 1894 that ended up as law.
