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A $240M Nature & Culture Museum is under way in Milwaukee, set to open in 2027 with four floors of exhibits, a rooftop terrace, butterfly vivarium, planetarium and more. Construction challenges including logistics, unique concrete structure and cold weather conditions, but emphasis on safety, sustainability and connection to community. Built by Mortenson Construction and ALLCON.
Tue June 17, 2025 - Midwest Edition #13
Already being described as an iconic landmark for the state, the Nature & Culture Museum of Wisconsin will encourage visitors of all ages to explore and engage when it opens in early 2027. The 200,000-sq.-ft. structure will feature four floors of exhibits, a rooftop terrace, butterfly vivarium, planetarium, café, green space and parking garage.
"It's very rare for a community to build a new natural history museum; in most cases, museums do renovations and expansions," said Katie Sanders, the museum's chief planning officer. "To be part of the reimagining of a more than 140-year community treasure is the opportunity of a lifetime.
"For the construction workers, this is a particularly meaningful project, as it's a building they can visit with their friends and families and show off their craftsmanship for decades to come."
Designed by the architecture team Ennead Architects and Milwaukee's Kahler Slater, the museum will be at the corner of Sixth and McKinley streets in the Haymarket neighborhood adjacent to the city's Deer District. Although much work remains to complete the project, the $240 million investment is already making headlines as the largest cultural project in state history.
Mortenson Construction and ALLCON are leading the groundbreaking effort.
"Mortenson brings exceptional expertise with large projects, including museums, and the corporate infrastructure to take on such a large and highly complex project," said Sanders. "ALLCON brings the ability to engage a hyperlocal workforce and some of the smaller contractors that would normally not have the opportunity to work on such a large build.
"Together, Mortenson and ALLCON bring a creative and open spirit, willing to try new ideas and push each other outside of their comfort zones to realize the best possible outcome for Milwaukee and our future museum."
Sanders said that a great deal of thought went into the planning.
"When we onboarded our architects, exhibit designers and construction management teams, which we strategically did at the same time, we spent a lot of time learning about Wisconsin's natural and cultural assets and diversity.
"We took a tour throughout the state, visiting 28 natural and cultural sites, including Mill Bluff State Park, which inspired the design of the building. The geological formations of what was Glacial Lake Wisconsin 10,000 years ago spoke to what we heard from community members throughout our design process — the importance of water on Wisconsin's agriculture, industry, traditions and culture."
Milwaukee Public Museum render
In addition, the three entrances symbolize the three rivers that converge in Milwaukee and connect in a space called the commons, which features a sky light that carries natural light down through the building.
Orchestrating the transfer of objects that will be featured in the new space has also required a great deal of coordination.
"Moving the more than four million collections items is a multi-year process that involves many steps to ensure the objects and their records are properly preserved," said Sanders. "Inventorying began several years ago with staff taking high-resolution photos of each object, transferring all handwritten information associated with the object into a database, and then assigning a barcode to the object so, that when scanned, all of that data can be easily pulled up.
"Once inventorying is complete, the objects are ready to be packed. Packing looks different depending on the object's size, shape, material and environmental parameters. Objects like glass or ceramic vases are individually wrapped in acid-free tissue and padded in archival foam to protect them in transport."
For construction crews tasked with bringing the new museum to life, the project is not without its share of obstacles.
"Working in downtown Milwaukee presents logistical challenges, due to the site's size and limited space for materials," said Kurt Theune, Mortenson vice president and general manager. "Just-in-time deliveries are critical to keeping the site organized and ensuring all trades remain productive.
"Additionally, the museum's unique concrete structure adds complexity. No two floor plates are identical as the building rises, and the floating decks require additional shoring. Tight coordination across the team is essential to maintaining concrete pour dates and staying on schedule."
Mobilization began in June 2024. Demolition was completed before the current construction team arrived, but significant earthwork was required before the concrete structure could begin.
"Mass excavation took place in June and July, [2024] followed by fine grading," said Theune. "Many piles were driven before pouring footings. Toward the end of 2025, we will begin the finish site work, including installing a bioretention basin on the north end of the site."
Approximately 17,000 cu. yds. of dirt/material will be moved during construction. Crews have been working on the cast-in-place concrete structure, with underground electrical and plumbing work ongoing in the slab-on-grade areas.
Milwaukee Public Museum photo
In pouring the floors of the five levels, each requires shoring, rebar, column and shear wall formation and slab-edge forms. The structure is unique, featuring BubbleDeck void forms between the top and bottom rebar mats, which reduce the weight of the 17-in. thick concrete slab, while maintaining its structural integrity.
Parking garage foundations were completed between November 2024 and March 2025. Deep foundation H-piles were finished in October 2024, enabling the pouring of footings and pile caps, which wrapped up in November 2024. About the same time, concrete structure columns and shear walls began. The concrete structure is now complete through Level 3.
The concrete structure requires careful sequencing, with four deck pours per level.
"While one deck cures, crews form and pour shear walls and columns, keeping operations continuous," said Theune. "With five levels plus the roof, totaling 24 deck pours, this phase demands precision, coordination and efficiency to stay on schedule."
Cold weather affects concrete curing times and limits crane operations at low temperatures.
"To counteract this, we build temporary enclosures under each deck being poured, heating the structure from below," said Theune. "Concrete blankets also help retain warmth, ensuring proper curing. The men and women working in these conditions go above and beyond, tackling each challenge head-on to keep the project moving forward."
Pour completion is expected by the end of June 2025.
"This will allow for the start of construction on the building envelope, so we can be dried in before next winter, at which point the interior build-out will be fully under way."
Construction requires a range of heavy equipment, including Komatsu PC138 excavators; Caterpillar D5 dozers; dump trucks; New Holland skid steers; 10K telehandler forklifts; a Terex 100-ton lattice boom crawler crane; a Tadano 100-ton telescoping boom crawler crane; and a Potain Manitowoc tower crane that's 180 ft. tall with a 235-ft. jib. The cranes will be used to set the structural precast for the garage and the architectural precast for the building envelope.
Mortenson photo
The museum will feature a mix of materials, including cast-in-place and precast concrete, steel framing to support the architectural precast and curtain wall glass to provide natural light for reflection lounges and panoramic views of downtown Milwaukee for museum patrons.
As for the chief concerns when approaching this type of project, said Theune, "This isn't just about building a structure, it's about creating a space that inspires, educates and stands the test of time. Safety is our top priority, from on-site worker protection to long-term visitor well-being.
"Climate control, exhibit integration and sustainability are critical, ensuring the museum can safely house priceless artifacts, while providing an engaging experience. Mortenson's role is to bring expertise early, working side by side with partners to build with care, efficiency and a shared vision for the future."
Theune remarked it's humbling to build a space that future generations will remember, where students, families and visitors can learn.
"Mortenson is proud to be a part of Milwaukee's construction community, bringing together highly skilled local trades, partners and craftspeople to create something truly special. By combining our deep local roots with the best of our national expertise, we're ensuring this museum isn't just built well — it's built to serve, connect and inspire for generations to come." CEG
Birmingham, Ala., native Cindy RIley originally planned on a career in law, but during her sophomore year in college realized journalism was her true calling. A magna cum laude graduate of Samford University, Riley first worked in radio and TV. Named Best News Anchor, Best News Reporter and Best Investigative Reporter by the Associated Press, she interviewed numerous personalities, ranging from Dr. Henry Kissinger and President Bush to Michael Jordan and Captain Kangaroo.
As a print journalist, Riley has covered a variety of topics, including construction, business, health and the arts. In addition to CEG, her work has appeared in special reports for USA Today and the L.A. Times. Other publications have included New South Magazine, Portico, Thicket, Alabama Heritage, B-Metro, Business First and Birmingham Business Journal.