The Metropolitan Opera House (colloquially The Met) is an opera house located on Broadway at Lincoln Square in the Upper West Side of Manhattan in New York City. Part of Lincoln Center for the Performing Arts, the theater was designed by Wallace K. Harrison. It opened in 1966, replacing the original 1883 Metropolitan Opera House at Broadway and 39th St. With a seating capacity of 3,800, the current house is the home of the Metropolitan Opera Company, and also presents the American Ballet Theater in the summer months.

Planning for a new home for the Metropolitan Opera began as early as the mid-1920s, when the backstage facilities of the former house were becoming vastly inadequate for growing repertory and advancing stagecraft. The development that what would become today's Rockefeller Center was originally to have a new 4,000-seat opera house at its center, but financial problems and the following stock market crash of 1929 postponed the relocation of the Metropolitan Opera, and the complex became more commercial-based. With the development moving forward, John D. Rockefeller, Jr. replaced the opera house with a 70-story skyscraper, opened as the RCA Building in 1933. Young Rockefeller Center architect Wallace Harrison would be approached some 20 years later by officers of the New York Philharmonic Society and the Met to develop a new home for both institutions. As chief architect again for the development of Lincoln Center, Harrison was chosen to design the new opera house- to be built as the centerpiece of the new performing arts complex. After a long process of redesigns, revisions and opposing interests (provided by the Met wanting a more traditional design for its home, and the conflicting wishes of the architects of the other Lincoln Center venues), construction of Harrison's forty-third design of the Metropolitan Opera House began in the winter of 1963- the last of the three major Lincoln Center venues to be completed.

The new building officially opened on September 16, 1966, with the world premiere of Samuel Barber's Antony and Cleopatra.

The building is clad in white travertine and the east facade is graced with its distinctive series of five concrete arches and large glass and bronze facade, towering 96 feet above the plaza. The building totals 14 stories, 5 of which are underground.

On display in the lobby, and visible to the outside plaza, are two murals created for the space by Marc Chagall. The south wall holds the work entitled The Triumph of Music while the north wall contains The Sources of Music. 

The multi-story lobby is dominated by a concrete and terrazzo cantilevered stairway that connects the main level with the lower level lounges and upper floors. The centerpiece of the lobby is an array of eleven crystal chandeliers resembling constellations with sparkly moons and satellites; the auditorium contains 21 matching chandeliers, the largest of which measures 18 ft (5.5 m) in diameter. The chandeliers were donated by the Vienna State Opera as repayment for American help in its reconstruction after World War II.  Twelve of the chandeliers in the auditorium are on motorized winches, and raised to the ceiling prior to performances so as not to obstruct sight lines of the audience on the upper levels. The lobby also contains sculptures by Aristide Maillol and Wilhelm Lehmbruck as well as portraits of notable performers and members of the Met company. A restaurant occupies space on the Grand Tier level, and spaces for patrons, guild members and the Metropolitan Opera Club exist as well throughout the lobbies. 

The Met is one the most technologically advanced stages in the world. Its vast array of hydraulic elevators, motorized stages and rigging systems have made possible the massive staging requirements of grand opera in repertory. The Met stage has also been home to several world premieres of operas, including Samuel Barber's Vanessa, John Corigliano's The Ghost of Versailles, Phillip Glass's The Voyage and the US premiere of Nico Muhly's Two Boys in 2013. Philip Glass's Einstein on the Beach was staged independently at the Met in 1976. Concerts by Barbra Streisand, The Who, Paul McCartney and others have been massively successful as well.

The auditorium is fan-shaped and decorated in gold and burgundy with seating for 3,794 and 245 standing positions on six levels. The square gold proscenium is 54 ft (16 m) wide and 54 ft (16 m) high. The main curtain of custom-woven gold damask is the largest tab curtain in the world. Above the proscenium is an untitled bronze sculpture by Mary Callery. The orchestra pit is very large and open to the auditorium, with the capacity for up to 110 musicians.

The stage complex is one of the largest and most complex of its kind in the world, extending 80 ft (24 m) deep from the curtain line to the rear wall. The overall dimensions of the stage with wing space are 90 ft (27 m) deep and 103 ft (31 m) wide.[13] The stage contains 7 hydraulic elevators that are 60 ft (18 m) wide, with double decks; three slipstages (large spaces on either side of and behind the main stage, each capable of holding a complete stage setting), the upstage one containing a 60 ft (18 m) diameter turntable; 103 motorized battens (linesets) for overhead lifting; and two 100 ft (30 m)-tall fully enveloping cycloramas. The large and highly mechanized stage and support space smoothly facilitates the rotating presentation of up to four different opera productions each week. The auditorium only makes up around 1/4 of the entire building- massive storage spaces below the stage allow for production storage within the opera house, and large workshops for scenery construction, costumes, wigs and electric equipment, as well as kitchens, offices, an employee canteen and dressing room spaces for the principals, chorus, supernumeraries, ballet and children's chorus surround the stage complex on multiple floors. Two large rehearsal halls (situated three floors below the stage) have nearly the dimensions of the Main Stage, allowing for blocking rehearsals and space for full orchestra set ups.