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Denver Art Museum’s New Grand Stair

Stephanie Randazzo Dwyer & Lucia Valentin   May 2020

View of the Main Public Stair from Duncan Hall – Photo by James Florio
The New Sie Welcome Center and Its Main Public Stair

The story behind the Welcome Center's new public stair, its innovative use of terrazzo and the reimagining of Gio Ponti's work as a form preservation.


he Denver Art Museum’s campus is comprised of several notable works of architecture: The Martin Building, a 7-story museum tower originally designed by renowned Italian Architect Gio Ponti (1971); and the Hamilton Building, a bold angular building designed by Daniel Libeskind (2007) for the Museum’s temporary exhibition galleries.

As part of a long-term vision to create a more unified campus, the new Sie Welcome Center, located between the Martin and Hamilton Buildings, serves as a beacon and an anchor for Denver’s emerging cultural center. With a nod to Ponti, the 50,000-square-foot elliptical-shaped structure provides improved access and expanded visitor services for the Museum’s growing programs and visitorship.

Diagram showing visitor flow with the addition of the Welcome Center and restoration of the Ponti tube entrance

The Welcome Center provides a new more visible public entrance to the newly renovated Martin Building; an additional entrance, via the restored iconic Ponti tube—the original entrance to the Martin Building—is dedicated to visitor access related to the Museum’s Learning and Engagement Center. With multiple entrances both to the Martin Building and the broader Museum complex, the Welcome Center and its new main public stair provides and communicates a clear and continuous connection for visitors across the Museum’s three buildings.

The Main Public Stair: Re-Imagining Gio Ponti as a form of Preservation

The main public stair is the primary vertical circulation device (outside of elevators) for public use and behaves much like several stairs in the original Gio Ponti-designed Martin Building. It connects Duncan Hall on the first floor to the Sturm Grand Pavilion on the second floor and a portion of the Bartlit Learning and Engagement Center on the Lower Level. The design and materiality of the stair draw inspiration from Ponti and his approach to the original design of the Martin Building.

Gio Ponti’s original curve based detail for existing terrazzo stairs common to the Martin Building’s public stairs (left) is also acknowledged in the new Welcome Center stair (right)

Inspired by Gio Ponti’s use of terrazzo in the Martin Building to create textured, light and reflective surfaces, the main public stair was idealized as a monolithic piece, all to be made of terrazzo. The terrazzo stair’s hard but beautiful texture creates something of a vertical, elliptical portal that gathers light from the event space’s expansive glass exterior.

Gio Ponti’s tube entrance - 14th Street entry (left); Original Ponti terrazzo stair at the Creative Hub, Martin Building (right) – Photos by James Florio

In the tower, Ponti occasionally used single runs of stairs to link notable spaces in a grand formal gesture of public circulation. In the Sie Welcome Center, the main stair spirals visitors off of Duncan Hall and up into the elliptical Sturm Grand Pavilion in a thrilling experience, with visitors being conveyed from the linear and lower space of Duncan Hall into the circular and grand space of the Pavilion. The notion of moving through an elliptical shaped portal is borrowed from Gio Ponti’s own design for the 14th Street Entry which uses a stainless steel horizontal portal to bring visitors from the street into the Main Hall.

Section of the Welcome Center’s Main Public Stair, running from the lower level, which features portions of DAM’s Learning and Engagement Center, to Duncan Hall on the first floor, to the Sturm Grand Pavilion on second floor

At the First Floor several treads of the up-stair “spill” out into the Main Hall signaling the uniqueness of the ascent. At the Events level the elliptical shaft of the stair extends upward forming a balustrade where visitors looking over might see the arrival of friends or family. At the Lower Level the stair connects to the expansive educational offerings and out into the revitalized Kemper Courtyard.

Layout drawing for new Welcome Center stair (left) and construction photograph (right)

The Geometry: Ellipses as the Counterpoint Geometry

There are artifacts of Gio Ponti’s design that are references and inspirations for Machado Silvetti’s conception of the Welcome Center. As seen with the tube entrance, the curved profiles at the tower’s crown and an unrealized elliptical auditorium, Gio Ponti introduced the ellipse as a counter point to the castle like geometry of the main building.

Gio Ponti’s site plan showing an elliptically shaped auditorium which was never realized

The new Welcome Center, located between the Denver Art Museum’s Hamilton Building and the North Towers, sits among many buildings which are large and have formally distinct architectures. This diversity, while emblematic of the Denver Art Museum’s approach to collection and exhibition, contributes to a lack of cohesion for the Museum complex. From the very beginning of the project, it was clear to the design team that the Welcome Center needed to be a unifying element among these many disparate buildings; a simple form to collect all of the diversity—an ellipse. This elliptical form became the basis for the geometry of the Welcome Center and, in turn, its main public stair.

Sequence diagrams showing geometry composition of the Sturm Grand Pavilion plan

The stair is formed by elliptical geometry in plan, and spun into a spiraling section. The primary runs of stair are formed from half of a base ellipse with an axis of 37’ and 25’-6 1/2”. This creates runs of spiraling stairs with alternate “landings” of real floor and traditional landing.

A central spiraling balustrade is formed by placing the vertex of a central, smaller ellipse (of 10’ by 5’ axis length) tangent to the bisector of the base ellipse so that the run of stairs is captured between the base ellipse and the central ellipse.

The center ellipse is stretched out like a ribbon in section to act as both the stringer and the balustrade for the stair. Treads are placed in a fanned out geometry so that they maintain minimum requirements for tread depth.

Photograph of new Welcome Center stair and the Sturm Grand Pavilion curtain track

The Construction: Terrazzo as the Means to Innovate

The form and curvature of the Main Public Stair required the use and innovation of different applications of terrazzo, old and new, to minimize joints and achieve continuous and smooth horizontal and vertical surfaces. The terrazzo applications include: pre-cast terrazzo for the treads, poured terrazzo for landings and hand-troweled and hand polished terrazzo for the guardwalls.

Given the ambition and anticipated complexity behind the Denver Art Museum project, Saunders Construction was brought on board early in the project as the Construction Manager. One of the great benefits of having Saunders involved early on, was that they were able to bring in the trades-people, and in this case the craftsmen, that were truly knowledgeable about working with terrazzo. This specific sub-contractor was Colorado Design, who worked with the design team to help envision the best way to achieve the monolithic terrazzo details.

Construction photos of guardwall substructure (top left); Construction photo after hand-troweled and hand-polished terrazzo (top right); Construction Mock Up for terrazzo treads and guardwall to test level of accuracy with hand troweling and hand polishing (bottom left); Troweled terrazzo installation at guardwall and installation of precast terrazzo treads (bottom right)

In order to ensure to all that the hand troweling and hand polishing would be able to achieve an acceptable level quality on a curved surface, the design and construction team and client agreed that a mock-up would be critical. It included a section of the stair with the tightest radius since this would be the most challenging for the hand work. The mock-up was extremely useful and allowed the design and construction team to be able to communicate expectations and challenging areas that would need to be improved upon. The design team worked directly with Colorado Design and Saunders on revising some details where multiple trades overlapped, like for example where a SS trim piece at the perimeter of the risers and treads met the vertical guard rail.

Looking down the Main Public Stair from the 2nd floor Sturm Grand Pavilion – Photo by James Florio

Project Credits

Owner: Denver Art Museum
Lead Designer / Associate Architect: Machado Silvetti
Architect of Record: Fentress Architects
General Contractor: Saunders Construction
Terrazzo Sub-contractor: Colorado Design
Photographs: Authorship noted in captions
*All drawings and renderings are attributable to Machado Silvetti and Fentress Architects

Read more related content:
DAM Project Story
DAM Welcome Center Glass
Denver Art Museum
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