In the closing decades of the 19th century, New York underwent a profound physical and cultural transformation. Fueled by the wealth of the exploding financial and manufacturing sectors, the city rapidly evolved into a world-class metropolis. The bold ambitions of civic and business leaders, architects, and engineers of the era manifested in landmarks such as the vast Cathedral of St. John the Divine, the stately U.S. Custom House, the towering Municipal Building, and the original terminus of New York City’s first official subway line—the ornate City Hall stop. The sweeping interior spaces common to all of these structures, and hundreds of others, depended upon a venerable Mediterranean building technology adapted to contemporary American construction: arched tile ceilings—or vaults—that were not only self-supporting but could also bear the weight of floors or roofs above them. These vaults were designed and built by a single New York firm, founded by Spanish immigrant Rafael Guastavino (1842-1908) and later headed by his son Rafael Jr. (1872-1950). The Guastavinos’ patented system for building domes and vaults involved multiple layers of thin ceramic tiles bonded with quick-drying mortar. The resulting structures were not only exceptionally strong, but also lightweight, easy to build, and inherently beautiful, thanks to intricate patterns of exposed tile that formed finished, decorative surfaces. Guastavino vaults figured prominently in more than 1,000 projects across the nation, including 200 in Manhattan alone. During its 73-year history, the Guastavino Company helped build some of the most impressive interior spaces in America—veritable palaces for the people. This list based on MCNY's exhibition Palaces for the People, contains many of Guastavino's masterpieces in the five boroughs, both those that remain and those that have been lost to the wrecking ball.

The Knights of Pythias are a fraternal order (or perhaps better described as a secret society) established in 1864 by Justus H. Rathbone, an upstate New York-born actor, composer, and teacher. Inspired by Irish writer John Banim’s 1821 play 'Damon and Pythias,' Rathbone founded this order on the principles extolled in the drama: friendship, loyalty, and honor. And as with most secret societies, pageantry, rituals, and costumed ceremonies were also important aspects of membership. The Manhattan lodge began assembling lots on West 70th Street for a clubhouse. Similar to other fraternal orders, the Knights of Pythias were interested in exotic architecture and turned to famed theatre architect Thomas Lamb for their Egyptian-themed home. Situated among the brownstones of an UWS side street, the tall building bedecked with cast stone reliefs, polychrome full-sized pharaoh figures, and an over-the-top entrance embellished with Egyptian symbols certainly was eye-catching. As ornate on the interior as the exterior, the building featured a gymnasium, a bowling alley, billiards room, 15 lodge rooms decorated in Aztec, Egyptian, and Moorish motifs, and two large auditoriums. The building served not only the Knights but hosted sermons for large synagogues and churches, dances and concerts, and political conferences and meetings (including by the 1940s civil rights groups, the Socialist Labor, and the West Side Committee of American-Soviet Friendship). One of the main auditoriums also served as a recording studio for Decca Records in the 1950s. New York Institute of Technology bought the foreclosed building in 1957 and discovered the kinds of strange props like wands and skeletons, both plastic and human! After functioning as an education space for NYIT, the building was converted into apartments between 1983 and 1986.

Church of the Blessed Sacrament, ca. 1919. This Catholic parish was established in 1887. The very first mass was celebrated on Easter Sunday of that year in a stable building on 72nd Street. Only a few months later, ground was broken for the first church, an Italianate red brick structure. The moderately sized building quickly outgrew the expanding congregation. The first church was demolished in 1917 and its replacement completed in 1920. The neo-Gothic building is elaborate inside and out and has a large colorful rose window directly above the entrance.