All architects have disappointments. Even the greatest are afflicted — perhaps they more than others. When they are younger, the pain is for the most part private, kept well concealed from view. It doesn’t pay to be a sore loser.

Architects know all about losing. Most important projects are awarded by competition and everybody loses more than they win. Even when you win a competition, you can still lose the project, for any number of reasons. Only architects in the evening of their professional lives can tell it like it really is.

Only they have the necessary distance and perspective to transform personal losses into lessons for us all. Lost Architectures, an exhibition by Barcelona’s MBM Arquitectes at the RIAI’s architecture centre in Dublin, offers a revealing glimpse of the battlefield that is international architectural practice.

Founded in 1951, MBM’s pioneering work in transforming Barcelona’s public spaces during the 1980s earned a worldwide reputation for Josep Martorell, Oriol Bohigas and David Mackay. Here they show 32 of their stillborn projects — “the ones that got lost along the way,” as Mackay puts it.

The exhibition dates from 2000, when Bologna was European city of culture. It was first shown in Bologna’s facsimile reconstruction of Le Corbusier’s seminal temporary Pavillon de L’Esprit Nouveau, built for the exhibition of decorative arts in Paris in 1925.

The venue shaped the exhibition’s content. “It was by his courage more than the magic of his pencil that we wished to remember the author of the pavilion,” says Mackay. “When he received the Royal Gold Medal for Architecture in London in 1953, Le Corbusier spoke of his failures.

“Now, after 50 years of architecture, we are guilty of the crime of being on the scene too long. This has given us, too, the opportunity to accumulate many failures.”

The failures — beginning in Barcelona in 1952 and continuing over the decades through Germany, France, Italy, Great Britain, Holland and Qatar — offer a rare opportunity to reflect on the reasons, the trends, and the architectural culture of the time.

Although there are positive failures among the exhibits, such as the Rosa Regás house in Girona, which became the inspired model for numerous house designs by MBM, right up to the present day, the lasting impression is of architecture’s unsustainable wasteland of creative output.

Bohigas puts it bluntly: “These failures were influenced by the senselessness of the competitions, a lack of understanding by the politicians, a lack of trust on the part of the clients, insufficient financing and, without doubt, also some mistakes on our part — at times too far removed from reality and not clever enough to hide the fact.”

Reality changes. MBM are now working in Dublin, a city that was derelict as recently as the 1980s. Many of the most forlorn sites of the time were owned by Dublin Corporation, having been acquired and cleared for road widening. In a society with little ambition and a poor grasp on communal values, the city’s traditional urban qualities — its complexities of scale and continuity — were being systematically eroded.

In the absence of a city architect, the parks department was often called in to ameliorate the worst of the damage done by the roads and traffic department. That’s how the millennium garden on Dame Street, beside City Hall, came about in 1988. During the 1970s city road engineers planned to widen Dame Street, and this had set in motion a sequence of events that resulted in the demolition of all the buildings in the block between Exchange Court and Palace Street, apart from the former Sick and Indigent Roomkeepers’ Society building.

The garden was the city’s weak and fussy attempt at disguising the dereliction it had brought about. With its three raised, decorative discs, two of them grassy and the other a reflecting pool for monumental sculpture, it is a pleasant enough setting for summer sandwich eaters. But it has none of the intimacy one finds in New York’s pocket parks, for example.