[4] As part of the construction of the line, the Hudson and Manhattan Railroad's (now PATH) 23rd Street station had to be rebuilt to provide space for the Sixth Avenue Line's 23rd Street stop, which was to be built at the same level as the Hudson and Manhattan's stop.

[12] Ground was broken for two new express tracks between the West Fourth Street and 34th Street–Herald Square stations on April 19, 1961.

[22] The subway station was closed for renovations on July 23, 2018,[23] and reopened slightly ahead of schedule on November 29, 2018.

A similar trim line is present on the platforms walls, though is higher and thus is regularly obscured by the angled ceiling supports.

Small tile captions reading "23" in white lettering on black run below both trim lines.

It is composed of 11 glass tile mosaics of Wegman's Weimaraners (a breed of dogs), each of which is wearing different attire.

The southern entrances on each side contain simple gray steel fences and are maintained by the Port Authority of New York and New Jersey, PATH's operator, rather than the Metropolitan Transportation Authority, the New York City Subway's operator.

The southern entrances appear to be part of the original PATH station, which was built in 1911.

[30] The northern entrances on each side contain green-metal fences that are standard to the New York City Subway, with countdown clocks showing the time until the next train arrives.