The Synodal Znamensky Cathedral, also known as the Cathedral of Our Lady of the Sign, is a stavropegial house church of the Russian Orthodox Church Outside Russia. It is located in a mansion at the intersection of Park Avenue and 93rd Street in the eastern part of Manhattan. This building also houses the Archdiocesan Synod of the Russian Orthodox Church Outside Russia and the residence of the First Hierarch. The cathedral is led by Metropolitan Hilarion (Kapral) of Eastern America and New York. The main shrine of the Russian Orthodox Church Outside Russia, the Kursk-Root Icon of the Mother of God, is kept here.

After World War II, it was decided to move the Archdiocesan Synod of the Russian Orthodox Church Outside Russia from Europe to the USA, which took place in 1950. Prince Sergey Beloselsky-Belozersky provided his country estate in Mahopac for the needs of the Synod, but due to its remoteness from the residences of Russian émigrés, it was decided to relocate the administration to Manhattan, at 312 West 77th Street, in 1952.

American banker of Russian descent Sergey Semenenko, upon learning of Metropolitan Anastasy's move to New York, decided to help find a more suitable building for the Synod. With the assistance of Mikhail Grigoryevich Shcherbinin, the Palmer-Baker mansion on East 93rd Street was found, which Semenenko purchased and gifted to the Synod in 1957. The consecration of the building took place on February 2, 1958, and in the summer of the same year, the Synod moved there. A memorial plaque was installed on the building with the inscription "Memorial Semenenko."

The mansion's ballroom was converted into a cathedral church in honor of the Icon of the Mother of God "The Sign," consecrated on October 12/25, 1959. The icons for the iconostasis were painted by Archimandrite Cyprian (Pyzhov). The miraculous Kursk-Root Icon of the Mother of God was placed in a kiot to the left of the solea, and during its pilgrimage, it is replaced by a copy, also painted by Archimandrite Cyprian. The enthronements of the First Hierarchs of the ROCOR take place here.

The former main dining room was converted into a church in honor of St. Sergius of Radonezh, where daily services are held, including early services in English for Orthodox Americans.

The main living room was transformed into the Synodal Hall for meetings of the Archdiocesan Synod. In the 1990s, the financial situation of the ROCOR was so difficult that the sale of the synodal building was considered.