Construction of Fifth Avenue began in 1824. Washington
Square, where 5th Avenue begins, became a public park in 1827. The original Memorial Arch
was erected on Fifth Avenue, near Washington Square, in 1889, for the
celebration of the centennial of Washington's Inauguration. The present arch at
Washington Square was dedicated in 1895. It marks the beginning of Fifth Avenue.
In the 1850s, Fifth Avenue gained momentum in its transformation from a predominantly residential area, place to mansions, to becoming a fashionable thoroughfare, with cultural institutions and luxury hotels. The Hotel St. Germain opened in 1856, at the junction of Broadway and Fifth Avenue, at 22nd Street. That was before Flatiron Building was constructed on the site, in 1901/1902.
now part of the site of the The Fifth Avenue Hotel opened in 1859 a little further north at 23rd Street, facing Madison Square.
