Pomo summer: the Piazza d'Italia in New Orleans, designed by Charles Moore, is one of the few icons of Postmodern architecture that isn't a building, and is next in our summer season on Postmodernism.

Both a memorial and a public space, the piazza is a manifestation of Moore's ideas of an "inclusive" architecture, which can speak to and be enjoyed by anyone. Moore's design, however, immediately attracted both fans and detractors, and many saw his architectural populism as pure kitsch.

Completed in 1978, the piazza was conceived as an urban redevelopment project and a memorial to the city's Italian citizens – past and present. The contributions of the Italian community had been largely overshadowed by those of the French, Spanish, African and Native Americans, according to the Italian-American community leaders that commissioned the project.

Moore took a highly pictorial approach to designing his urban plaza. Colonnades, arches and a bell tower are arranged in a curving formation around a fountain. The layers of structures are brightly coloured, trimmed in neon and metallics, and ornamented with various classical orders. The paved surface of the plaza is equally embellished and textured. Light and shadows play across the surface of the plaza, and views through the various openings create a complex spatial experience for visitors moving through the colonnades. Uplighting and neon accents animate the space at night.

While other Postmodernists – as they would later be known – like Michael Graves and Philip Johnson used classical elements to poke fun at Modernist orthodoxy, to telegraph knowing commentary or even jokes to architectural insiders, Moore insisted his colourful, cartoonish piazza was a joyful tribute. It was a monument to the achievements of Italians, so it references Italian culture directly – the country's architecture, urbanism, and geography are all represented.

Opinions about the design are sharply divided. The intricate drawings for the then unbuilt project won a Progressive Architecture award in 1976. In his 1993 obituary for Moore, New York Times critic Herbert Muschamp called the project a "festive agglomeration of semi-circular colonnades, neon arches and fountains". And Charles Birnbaum, president of the Cultural Landscape Foundation, told Dezeen the piazza is a "seminal Postmodern landscape".

Others are not so convinced. Writing in Landscape Architecture Magazine in 2004, the commentator Allen Freemen wittily characterised it as "like one of those fruity, rummy Hurricane cocktails that you sip through a straw from a curvy glass garnished with an orange slice and maraschino cherry: colourful, over the top, and made of questionable ingredients". Sounds like a recipe for an architectural hangover.

Moore's agenda for Postmodernism in architecture was inclusive and democratic. While Aldo Rossi wanted his buildings to resonate with memory, and Robert Venturi and Denise Scott Brown wanted their buildings to communicate, Moore wanted his buildings to inspire joy and connect to everyday people.

Moore's mission of inclusivity was largely accomplished, at least as far as his client constituency is concerned.

The website of the American Italian Cultural Center, which is located adjacent to the piazza, characterises it thus: "Great Architecture tends to inspire admiration reverence, humility, awe, and other such solemn emotions. But rarely does it fill its beholder with feelings of happiness, joy, warmth, and love. The Piazza d'Italia is one of those exceptions… [it] forms an ensemble of unqualified pleasure and delight, the perfect expression of the gloria di vita that is characteristically Italian as the vocabulary of form and colours that make this such a deeply evocative place."

Born in 1923, Moore graduated from the University of Michigan in 1943 and went on to study at Princeton, where he earned a Masters and PhD. Moore was a polymath: an architect and planner, a prolific writer, and teacher. He was also a nomad. After a period as a teaching assistant for Louis Khan at Princeton, he taught at Berkley, Yale, the University of California and there University of Texas, setting up different architecture firms as he moved around.

His writing and academic life clearly informed his architecture. Perhaps the figures that Moore is most closely entwined with aesthetically and philosophically, and with whom he shared affinities and differences, are Venturi and Scott Brown. Their writing appeared together in a seminal 1965 issue of Perspecta, Yale's architecture journal, edited by then student Robert A M Stern.

Venturi contributed an excerpt of Complexity and Contradiction in Architecture, which would go on to be one of the most important treatises of architectural Postmodernism. Moore put forward the brief essay You Have to Pay for the Public Life, his best-known piece of writing. Both texts drew on vernacular, popular, and commercial buildings as sources for architectural investigation.

In Public Life, Moore argued – somewhat paradoxically – that within the highly privatised landscape of Southern California, Disneyland offered the best example of public space. Within the architectural establishment, still steeped in High Modernism, the suggestion that Disneyland was a subject worthy of serious investigation was a radical notion.

Moore went on to become dean of the Yale School of Architecture, and soon brought Venturi and Scott Brown to teach there. They famously created the so-called Las Vegas studio, researching the buildings, signs, and communicative forms of the Strip and of American road culture in general, the findings of which ultimately became the book Learning from Las Vegas.

While Moore supported their research as dean, he had mixed feelings about Learning from Las Vegas, according to Jimmy Stamp, a writer who is co-authoring a history of the Yale School of Architecture with Stern, Yale's current Dean. "Moore found Complexity and Contradiction 'thrilling' in its inclusiveness. But he viewed Learning from Las Vegas differently, calling it an 'embattled book' in his review for Architectural Record."

"Although Moore appreciated its exaltation of symbols, he was uneasy with the aggressive dialectic the book established between ugly/ordinary and heroic/original. Where was the inclusiveness in that?" Stamp told Dezeen. "He viewed Vegas itself as a heroic construct, perhaps in the same way he saw Disneyland's Matterhorn as a California monument."

Arguably there is something of both Vegas and Disneyland to be found in the highly scenographic and theatrically lit Piazza d'Italia. The Venturis, too, deployed a highly scenographic style, but Stamp says "sincerity" differentiates Moore's work from that of the Venturis more cerebral – some might argue cynical – uses of signs and symbols.

Sincerity, apparently, did not vanquish humour in Moore's piazza. Fountains of Moore's own likeness spew water from their mouths, pursed in gleeful smiles, in arcs on the plaza.

The Cultural Landscape Foundation's Birnbaum argues it is important to understand Moore's sensitivity to landscape, and to consider the Piazza d'Italia as a work of landscape architecture.

According to Birnbaum, Moore expressed great admiration for the discipline of landscape architecture and said he often wished he had become a landscape architect. He worked for the noted landscape architect Lawrence Halprin in the early 1960s and went on to collaborate with him on several key projects over then next 20 years.

Moore's masterwork, the Sea Ranch vacation community, designed with Halprin, straddles the rocky California coast. It is an austere set of buildings clad in vertical redwood, which, together, form a village through their Italian hill town-like arrangement and deep connection to the dramatic landscape. Though spartan on the outside, inside many of the condominiums were decorated with bright and bold supergraphics, which were common in many of Moore's interiors.

At the piazza, Moore turns this decoration inside out. He spatialised the symbols of culture and heritage to become a landscape.

In You Have to Pay for the Public Life, Moore wrote that Disneyland was a place "full of sequential occurrences, of big and little drama, hierarchies of importance and excitement". Some of this thinking likely went into his design for the piazza.

Unlike the fully privatised – and meticulously maintained – Disneyland, the Piazza d'Italia suffered from decades of neglect, and it failed to spark the hoped-for revitalisation of downtown New Orleans.

Happily for its fans, it was fully restored in 2004, so it will continue to confound architecture buffs and please members of the public for decades more to come.

Photography is by Kevin Keim.