Question: What is being built both at 3 Hudson Boulevard and 520 Park Avenue?

Context paragraphs:
Mount Royal Avenue: Mount Royal Avenue (officially in French: avenue du Mont-Royal ), once named Tannery Road (French: chemin des Tanneries ), is a street in Montreal.  The main part of the street transects the borough of Le Plateau-Mont-Royal, from Park Avenue at the foot of Mount Royal, for which the road is named, to Frontenac St. Another section in Rosemont–La Petite-Patrie runs from Molson St. to Pie-IX Boulevard.  West of Park Avenue, the road continues into Outremont (where it becomes "Mount Royal Boulevard"), skirting the northern rim of the mountain until Vincent d'Indy Avenue.

520 Park Avenue: 520 Park Avenue is an American skyscraper under construction on East 60th Street west of Park Avenue in Manhattan, New York City.  It was designed by Robert A.M. Stern Architects.  The building will cost US$450 million to build.  The tower will be completed by 2017.  It is a Zeckendorf development.

Deering Oaks: Deering Oaks is a 55 acre public park in Portland, Maine, which has a baseball diamond, tennis courts, a playground, and a pond.  It is located west of downtown Portland and is bordered by Deering Avenue on the west, Forest Avenue on the east, Park Avenue to the south and Interstate 295 to the north.  State Street bisects the park.  Access is from State Street, Deering Avenue, or Park Avenue.  The Portland Farmers Market is located on the Park Avenue side of the park.  The park is listed on the National Register of Historic Places.

Park Avenue: Park Avenue is a wide New York City boulevard which carries north and southbound traffic in the borough of Manhattan.  For most of the road's length in Manhattan, it runs parallel to Madison Avenue to the west and Lexington Avenue to the east.  Park Avenue's entire length was formerly called Fourth Avenue; the title still applies to the section between the Bowery and 14th Street.  Meanwhile, the section between 14th and 17th Street is called Union Square East, and between 17th and 32nd Streets, the name Park Avenue South is used.

Church of St. Ignatius Loyola (New York City): The Church of St. Ignatius of Loyola is a Roman Catholic parish church located on the Upper East Side of Manhattan, New York City, administered by the Society of Jesus (Jesuits).  The parish is under the authority of the Archdiocese of New York, and was established in 1851 as St. Lawrence O'Toole's Church.  In 1898, permission to change the patron saint of the parish from St. Lawrence O’Toole to St. Ignatius of Loyola was granted by Rome.  The address is 980 Park Avenue, New York City, New York 10028.  The church on the southwest corner of Park Avenue and 84th Street is part of a Jesuit complex on the block that includes Wallace Hall, the parish hall, beneath the church, the rectory at the midblock location on Park Avenue, the grade school of St. Ignatius's School on the north midblock location of 84th Street behind the church and the high school of Loyola School (also 980 Park Avenue) at the northwest corner of Park Avenue and 83rd Street.  In addition, another Jesuit high school, Regis High School (55 E 84th Street), occupies the midblock location on the north side of 84th Street.  The church was added to the National Register of Historic Places on July 24, 1980.

Myrtle Avenue (BMT Lexington Avenue Line): Myrtle Avenue was a station on the demolished BMT Lexington Avenue Line.  It was opened on May 13, 1885 had two tracks and two side platforms.  It was located at the intersection of Myrtle Avenue and Grand Avenue in Brooklyn, and had connections to Myrtle Avenue Line streetcars.  A segment of the Lexington Avenue Line once ran north from here and turned west on Park Avenue to Hudson Avenue and York Street on its way to the Fulton Ferry until 1891.  The Myrtle Avenue Elevated was built nearby in 1888, and Lexington Avenue Lines trains began to shift onto that line southwest of this station.  It closed on October 13, 1950, although the other BMT station at that location, Grand Avenue was in operation until January 21, 1953, while the rest of the line southwest of Broadway was operational until November 3, 1969.  The next southbound stop was Washington Avenue on the Myrtle Avenue El, but was originally another Washington Avenue station on the Park Avenue El.  The next northbound stop was DeKalb Avenue.

Tinley Park station: Tinley Park Station (also known as Tinley Park-Oak Park Avenue Station) is an elaborate commuter railroad station along Metra's Rock Island District line in Tinley Park, Illinois.  The station is officially located at 6700 South Street between Oak Park Avenue and 66th Court, however parking is also available on the opposite side of the station along North Street between Oak Park Avenue and 67th Avenue, as well as the center of the block of Oak Park Avenue, 173rd Street, 67th Court and 172nd Street.  Another parking area exists along South Street opposite the main parking lot at the station.  The station itself is lies 23.5 mi away from LaSalle Street, the northern terminus of the line.

Lake Washington Boulevard: Lake Washington Boulevard is a scenic, approximately 8 mi , route through Seattle, Washington, that hugs Lake Washington for much of the drive.  There are views of the lake, small sections of rainforest, meadows, and views of the Cascade mountains.  At its northern end, Lake Washington Boulevard originates as East Lake Washington Boulevard at Montlake Boulevard East, soon becomes Lake Washington Boulevard East, and runs through the length of the Washington Park Arboretum.  The road begins at S. Juneau Street in Seward Park, running thence along the lake to Colman Park, just south of Interstate 90.  From here north to E. Alder Street in Leschi, the lakeside road is named Lakeside Avenue, and Lake Washington Boulevard diverts to a winding route through Colman, Frink, and Leschi Parks.  At E. Alder, the boulevard once again runs along the lake through Madrona Park to just north of Madrona Drive, where private residences occupy the shore.  At E. Denny-Blaine Place, the road heads northwest, through Lakeview Park and the grounds of The Bush School, to the south entrance of the Arboretum at E. Madison Street.  It continues through the Arboretum.  Just north of E. Roanoke Street, the boulevard turns due west and changes from Lake Washington Boulevard E. to E. Lake Washington Boulevard, following the city's street name designation system.  The boulevard ends at the Montlake overpass of 520, where E. Montlake Place E. becomes Montlake Boulevard E.

Park Avenue station (Charlotte): Park Avenue was a station on the Charlotte Trolley heritage streetcar line in South End of Charlotte, North Carolina, United States.  The station first opened for service on August 30, 1996, with one track and one platform, located south adjacent to Park Avenue.  After nearly a decade of service, the station was permanently closed on February 6, 2006.  The relocation of Bland Street station, for the LYNX Blue Line, and the already close proximity of East/West Boulevard station made Park Avenue redundant and thus unnecessary.  By end of 2006, the side platform and structure was razed; what remains at the former location are some brick and concrete foundation and a stone pattern walkway connecting to Park Avenue.

3 Hudson Boulevard: 3 Hudson Boulevard, previously tentatively known as the GiraSole, is a supertall skyscraper under construction in Manhattan's Hudson Yards and Hell's Kitchen neighborhoods along the Hudson Park and Boulevard in New York City.  Its developer is Joseph Moinian.

Supporting paragraphs: 3 Hudson Boulevard 520 Park Avenue
Answer: an American skyscraper under construction