Title: Kremlin Arsenal
Content:  The Kremlin Arsenal (Арсенал Московского Кремля) is a former armory built within the grounds of the Moscow Kremlin in Russia. Initially constructed in 1736, it has been rebuilt several times. It remains in military use to date, unlike the Kremlin Armoury, another arsenal within the walls of the Moscow Kremlin, which is now a museum. The building is off-limits to tourists, who can view a portion of its short southern façade upon entering the precincts of the Moscow Kremlin. The Kremlin Arsenal is currently home to the Kremlin Regiment, which forms the main security service for the Russian President, and the longer eastern façade is a high secured and restricted area closed to the public.
Title: Moscow Kremlin
Content:  to the east, and the Alexander Garden to the west. The name "Kremlin" means "fortress inside a city", and is often also used metonymically to refer to the government of the Russian Federation. It previously referred to the government of the Soviet Union (1922–1991) and its highest members (such as general secretaries, premiers, presidents, ministers, and commissars). The term "Kremlinology" refers to the study of Soviet and Russian politics. The Kremlin is open to the public and offers individual and group guided tours. Visible are the Armoury Chamber, Tsar Cannon, Tsar Bell, artillery pieces, and the exposition of Russian wooden sculpture and carvings.
Title: Moscow Kremlin
Content:  The State Kremlin Palace (alias Kremlin Palace of Congresses), was commissioned by Nikita Khrushchev as a modern arena for Communist Party meetings, and was built within the Kremlin walls 1959–1961. Externally the palace is faced with white marble and the windows are tinted and reflective. The construction of a large modern public building in a historic neighborhood generated an uproar, especially since the building replaced several heritage buildings including the old neo-classical building of the State Armory and some of the rear parts of the Great Kremlin Palace. Although this was not the first time that the Soviet government had destroyed architectural heritage (notably the Chudov Monastery and Ascension Cloisters) in the Kremlin and in the country in general, by the mid 1950s laws were in place effectively considering all pre-Soviet constructions as historical monuments and preventing their demolition, in some ways making the construction illegal. Nevertheless, the Palace was integrated into the larger complex of the Great Kremlin Palace with walkways linking it to the Patriarchal Chambers and the Terem Palace.
Title: Astrakhan Kremlin
Content:  At the beginning of the 20th century, after the October Revolution, access to the Territory of Kremlin was closed. Instead it was transformed as a military post, where groups of Red Guards were formed the Military Revolutionary Committee was placed. In January 1918 Astrakhan Kremlin was once again in the middle of fateful events, when supporters of Soviet power fought with Astrakhan Cossacks. They attacked The Red Army that was entrenched in the Kremlin, from the roofs of nearby buildings. Serious destruction was caused to the Kremlin after this battle. Miraculously the temples of Kremlin have survived. In 1919 the Army was reorganized under the leadership of Kirov to protect the outfall of Volga and to defeat the White Guard troops and foreign interventionists. Thus, in the early 20th century the Kremlin remained a military target. It was popularly named as “The Town of Trotsky” (in 1992-1926). Only after the end of World War II did the town open access to the Kremlin. At the same time, the Kremlin ceased to be subject of military purposes. In the middle of the 20th century, significant restoration works were held, due to which many buildings, requiring urgent repairs were saved.
Title: Moscow Kremlin
Content:  Although still used for coronation ceremonies, the Kremlin was abandoned and neglected until 1773, when Catherine the Great engaged Vasili Bazhenov to build her new residence there. Bazhenov produced a bombastic Neoclassical design on a heroic scale, which involved the demolition of several churches and palaces, as well as a portion of the Kremlin wall. After the preparations were over, construction was delayed due to lack of funds. Several years later the architect Matvey Kazakov supervised the reconstruction of the dismantled sections of the wall and of some structures of the Chudov Monastery, and built the spacious and luxurious Offices of the Senate, since adapted for use as the principal workplace 
Title: Kyivan Rus Park
Content:  The charitable organization "Slavic fund" was founded with the intention of creating a historical and cultural Center of Kyivan Rus'. The intent was to reconstitute and reconstruct the Kyiv Detinets (the fortified part of Kyiv in the 5th to 13th century) with a maximum of historical authenticity, cultural and architectonical characteristics, as well as recreating the atmosphere of the epoch of Kyivan Rus'. The reconstructed Kremlin was built using the research of Kyivan Rus' history: U. Aseev, M. Braychevskiy, G. Ivakin, S. Kilievich, A. Kutovoy, B. Rybakov, M. Tihomirov, P. Tolochko, I. Shevelev, and others.
Title: Kremlin Senate
Content:  The Kremlin Senate (The Senate Palace, Сенатский дворец) is a building within the grounds of the Moscow Kremlin in Russia. Initially constructed from 1776 to 1787, it originally housed the Moscow branch of the Governing Senate, the highest judiciary and legislative office of Imperial Russia. Currently, it houses the Russian presidential administration and is a highly secured and restricted area closed to the public. At present, only the southern corner façade, opposite the Tsar Cannon can be viewed.
Title: Grand Kremlin Palace
Content:   The Grand Kremlin Palace (Большой Кремлёвский дворец - Bolshoy Kremlyovskiy Dvorets), also translated Big Kremlin Palace or Great Kremlin Palace, was built from 1837 to 1849 in Moscow, Russia on the site of the estate of the Grand Princes, which had been established in the 14th century on Borovitsky Hill. Designed by a team of architects under the management of Konstantin Thon, it was intended to emphasise the greatness of Russian autocracy. Konstantin Thon was also the architect of the Kremlin Armoury and the Cathedral of Christ the Savior.
Title: Kremlin Presidium
Content:  The Kremlin Presidium (The Administrative Building of the Kremlin, Административный корпус Кремля), also denominated Building 14 (14-й корпус), was an edifice within the Moscow Kremlin in Russia. Constructed in 1934, until 2011 it housed, first, the Supreme Soviet, i. e. the supreme legislative body of the Soviet Union until its dissolution in 1991, and, second, the offices of the Presidential Administration of Russia. It was demolished in 2016.
Title: Kremlin Presidium
Content:  The Presidium was on the site of the former Chudov Monastery which Metropolitan Alexius of Moscow founded in 1365, Ascension Convent, and Lesser Nicholas Palace. These were among the historic edifices in the Kremlin that Joseph Stalin ordered demolished as part of the state atheism campaign, pursuant to which religious structures throughout Russia were razed. Ivan Rerberg, a prominent architect of Moscow who had designed the Kiyevsky Rail Terminal, was assigned to design a new administrative building for the Soviet government, and its construction began almost immediately. The new edifice was completed in 1934, two years after Rerberg's death. Initially it was not named, and it hosted the Red Commanders School, which was a military academy for Red Army leaders. The School was relocated in 1935, and from 1938 the building housed the offices of the Presidium of the Supreme Soviet, whose head was the de jure head of state of the Soviet Union. From 1958-61, part of the building was converted into the 1,200-seat Kremlin Theatre (Кремлёвский театр). However, it proved to be an awkward venue, and its functions were transferred to the newly built State Kremlin Palace.

Question: what was the original purpose of the kremlin?
Answer: the tsar's Moscow residence.