Euclid Avenue is the terminus of the local tracks of the IND Fulton Street Line (currently under Pitkin Avenue), and has four tracks with two island platforms. Express A trains (unless running local) stop on the middle tracks and local C trains on the side tracks. C trains drop there passengers off on the Queens-bound side track before relaying beyond the station to re-enter service on the Manhattan-bound side track. The area beyond the station also has yard leads to the Pitkin Yard. During late nights A local train service runs only to and from Far Rockaway, service to Lefferts Blvd is provided by a 4 car OPTO operated Yellow S Shuttle train. During late nights A local trains stop on the side tracks and Lefferts Blvd Shuttle trains terminate and originate on the express tracks relaying beyond the station (at the opposite side of the station from C trains).
The station is on the end of the Fulton Street Line that had tunneling completed before World War II (with stations as shells), but wasn't finished (with tracks and stations added) until after the war due to war time rations on construction materials, finally opening on November 28, 1948. In the eight short years since the completion of the IND Sixth Avenue Line (in 1940) the design for a subway station has changed and been modernized quite a bit. Euclid Avenue (along with the three local stations on the line that opened at the same time) have a bit of an unusual design for the tiling (the other Post World War II and 1950s and 1960s stations are similar-Grand Street, Grant Avenue, and 57 St/6 Ave). The tiles are more of a quite off white cream color instead of the standard white, they are also bigger. The station does have a trim like the standard IND Station with a dark purple boarder and a light purple center. There is Euclid tiling along the platform walls except it is simply directly written on the tiles on the walls, not in a separate white text with a black background format. All the pillars also are tiled, with the same purple trim on top, except the trim is expanded on two sides of them and Euclid is tiled. All in all the design of the Euclid Avenue station is a good example of the changes in American design between pre (most IND stations) and post World War II.
The station itself has one fare control area with staircases up to all four sides of Euclid Avenue. TInside of fare control there isn't one of the standard (for an express station) IND full-length mezzanines, instead there is a mezzanine of adequate size (with three staircases to each island platform) but nothing oversized like most IND stations. The platform seems a bit narrower compared to other IND Express Stations. Recently, in 2005 the station had a bit of a renovation with three elevators (one up to street level and one down to each of the platforms) added as well as some of the platform staircases modernized. The platform elevator shaft doors are all painted purple to go with the station's color scheme. Luckily the station's tiling went untouched, it's in extremely good repair.