Question: Metropolitan Life North Building is connected by an elevated walkway to a tower designed by which architectural firm ?
Context: Marks Barfield Architects is a London-based architectural firm founded by husband and wife David Marks and Julia Barfield.  Their work has included the London Eye, the treetop walkway in Kew Gardens and the i360 observation tower in Brighton, England.  In 2012 they were hired to design a six-mile rainforest canopy walkway for the Amazon Charitable Trust. The Anson Mills Building is a historic building located at 303 North Oregon Street in El Paso, Texas.  The Building stands on the original site of the 1832 Ponce de León ranch.  Anson Mills hired Henry C. Trost of the Trost & Trost architectural firm to design and construct the building.  Trost was the area's foremost pioneer in the use of reinforced concrete.  Built in 1910-1911, the building was only the second concrete-frame skyscraper in the United States and one of the largest all-concrete buildings.  At 145 feet (44 m), the 12-story Mills Building was the tallest building in El Paso when completed.  The architectural firm of Trost and Trost moved its offices to the building upon completion, where they remained until 1920.  The Mills family sold the building in 1965.  The building stands on a corner site opposite San Jacinto Plaza, with a gracefully curved street facade that wraps around the south and east sides.  Like many of Trost's designs, the Anson Mills Building's overall form and strong verticality, as well as details of the ornamentation and cornice, are reminiscent of the Chicago School work of Louis Sullivan. Jardine House (), formerly known as Connaught Centre (), is an office tower in Hong Kong.  The building is located at 1 Connaught Place, Central on Hong Kong Island.  It is owned by Hongkong Land Limited, a subsidiary of Jardines.  At the time of its completion in 1972, Jardine House was the tallest building in Hong Kong and in Asia.  In 1980, the Hopewell Centre usurped the title of the tallest building in Hong Kong.  The building is interconnected by the Central Elevated Walkway with buildings of Hongkong Land Limited like Exchange Square and the International Finance Centre. Virginia Flats, also known as the Summit Place Flats, are two historic apartment buildings located at St. Joseph, Missouri.  They were designed by the noted architectural firm Eckel & Mann.  The south building was built in 1901, and is a two-story, rectangular Colonial Revival style brick four-plex with a hipped roof and a full-length, one-story front porch.  The north building was built in 1888, and is a larger two-story rectangular brick Queen Anne style apartment building with 14 apartments, 7 on each floor. The Metropolitan Life North Building, now known as Eleven Madison, is a 30-story art deco skyscraper on Madison Square Park in Manhattan, New York City, at 11-25 Madison Avenue.  The building is bordered by East 24th Street, Madison Avenue, East 25th Street and Park Avenue South, and is connected by an elevated walkway to the Met Life Tower just south of it.  The North Building was built on the site of Richard Upjohn's original Madison Square Presbyterian Church.  The second church, designed by Stanford White of McKim, Mead and White was built in 1906, across 24th street on land conveyed by Metropolitan Life.  As part of the Metropolitan Life Home Office Complex, the North Building was added to the National Register of Historic Places on January 19, 1996. Theodore Conrad (May 19, 1910 – August 19, 1994) was an American architect, preservationist and a leading architectural model maker, often referred to as the Dean of Models.  Conrad was one of the first independent architectural model makers in the United States and contributed significantly to modern architecture through his collaborations with architects such as Harvey Wiley Corbett, Wallace Harrison, Skidmore, Owings & Merrill and Edward Durell Stone.  His most notable projects include models for the Metropolitan Life North Building, Rockefeller Center, Lever House, Seagram Building, the Manufacturers Trust Company Building and the John F. Kennedy Eternal Flame. The Former Mount Pleasant Public Library is a historic building located in Mount Pleasant, Iowa, United States.  The library here was established in 1875.  The community applied to Andrew Carnegie for a grant to build a new building, which was accepted on January 13, 1903.  They were initially granted $10,000 and then were given a further $2,500.  The Chicago architectural firm Patton & Miller designed the Romanesque Revival structure.  They adapted Henry Hobson Richardson's Thomas Crane Public Library (1882) for this building.  Unlike the Crane Library, this building is primarily brick with rough stone used for a short tower on the main facade and for the trim.  It also features an asymmetrical grouping of intersecting gables.  The building opened on Wednesday, February 22, 1905.  An addition was built onto the rear of the building in 1926.  It was designed by the Des Moines architectural firm of Dougher, Rich & Woodburn.  The building was listed on the National Register of Historic Places in 1983.  The library has subsequently moved to another facility and this building now houses a branch of Southeastern Community College. Leeds New Lane was a proposed new railway station to accommodate High Speed Two rail services in West Yorkshire, England.  It was planned to be constructed on a viaduct on New Lane south of Leeds city centre, the River Aire and Leeds City station to which it would be connected by an elevated walkway.  The site is occupied by "Central Park", a small low-rise office park built in the 1990s and other small office buildings. ZGF Architects LLP (ZGF), formerly Zimmer Gunsul Frasca Partnership, is an American architectural firm with offices in Portland, Oregon; Seattle, Washington; Los Angeles, California; Washington D.C.; New York, New York; and Vancouver, Canada.  Founded in 1942, the firm was listed in 2011 as the #4 architectural firm in the United States by "Building Design+Construction", and ranked the #9 architectural firm by "Architect".  In 2016 "Architect" named ZGF the #1 architecture firm in the country, citing the organization's dedication to sustainability as a major deciding factor.  Between the company's five offices in the United States and their office in Canada they employ more than 600 employees. The Metropolitan Life Insurance Company Tower, colloquially known as the Met Life Tower, is a landmark skyscraper located on Madison Avenue near the intersection with East 23rd Street, across from Madison Square Park in Manhattan, New York City.  Designed by the architectural firm of Napoleon LeBrun & Sons and built by the Hedden Construction Company, the tower is modeled after the Campanile in Venice, Italy.  The hotel located in the clock tower portion of the building has the address 5 Madison Avenue, while the office building covering the rest of the block, occupied primarily by Credit Suisse, is referred to as 1 Madison Avenue.
Answer: Napoleon LeBrun & Sons