With the Museo Soumaya, it’s safe to say Fernando Romero and his office LAR landed what might be defined as any architect’s dream job: the design of a museum to house the private art collection of the world’s richest man. So when, sometime later this year, it is completed, Romero – who Rem Koolhaas credits as the co-originator of OMA’s design for the Casa da Musica in Oporto – will likely have to stand up to some pretty exacting critical scrutiny.

Scrutiny of any kind is something both the building and its architect appear to unashamedly relish. Soaring skyward from a deep concrete plinth that conceals a capacious auditorium, a loading dock and a private entrance for the museum’s opulent patron, the museum will form the most iconic element of a new cultural pole that will also comprise David Chipperfield’s new Jumex Collection building (as well as Mexico’s largest car park – capacity 9,000 cars). The museum will be accessed via a broad stairway that climbs the southern side of this plinth, intended to elevate it above the northbound traffic of one of Distrito Federal’s busiest avenues.

According to Romero, the ground floor – largely designed for public functions and opening events – will host a single work on permanent display: Rodin’s Thinker. The lower, smaller floors of the museum will be used for temporary exhibits, while the upper levels will permanently house Slim’s personal and extremely eclectic collection. Items in this area will include not only undisputed masterpieces (including the second-largest cache of Rodin sculptures anywhere in the world in private hands), but also design objects and rare automobiles.

Although it is blindingly evident that the budget on this project was anything but tight, according to Romero it was not without constraints: the client insisted, in particular, he used as many of the firms owned by his company as possible. One of these is a manufacturer of tubular steel, the use of which as a structural system made the freeform exterior shape (engineered by ARUP) practicable; another is a producer of aluminium panels, now engaged in the fabrication of the museum’s tesselated hexagonal exterior cladding. Although it’s not yet in place, we are told the building’s skin will not allow views over the city, but will allow a certain amount of natural light to filter into the gallery spaces.

The building is organised around a central core containing lifts and stairs, intersected by a series of slabs supported by the tubular steel columns. As one rises up through the building along a ramp the core, the proportions of the spaces become more generous: a by-product of an increased floor-to-ceiling height, larger floorplan and lower density of columns. Circulation can occur either from the bottom to the top, climbing the ramps, or from the top downwards. One of the most impressive spaces is the below-grade auditorium, tucked under the entrance level at the point where the building’s skin swoops down at a sharp angle to meet the plinth.

If one were to characterise Romero’s work in a single sentence, one might say that more than buildings he creates urban objects – architectural entities which, at their most daring (and most interesting), appear to be momentarily touching the ground rather than permanently rooted to it. As in many other of his most radical projects (Villa S, Border Museum), Museo Soumaya’s footprint on the ground is much smaller than its floorplan – which of course is one of the defining features Casa da Musica itself, and gives it its powerful object-like quality within the urban context. We can only hope this flamboyant, optimistic museum’s architectural self-confidence won’t be undermined by the towering office complex currently under construction immediately to its north. Joseph Grima