Post-war Soviet Union

The main building Moscow State University was once the tallest in Europe.

Stalinist architecture put a premium on conservative monumentalism. In the 1930's, there was rapid urbanisation as a result of Stalin's policies. There was an international competition to build the Palace of the Soviets in Moscow in that decade.

After 1945, the focus was on rebuilding the buildings destroyed in World War II but also erecting new ones: seven high-rise buildings were built at symbolic points in Moscow's space. The building of Moscow University (1948-1953) by Lev Rudnev and associates is particularly notable for its use of space. Another notable example is the Exhibition Centre in Moscow which was built for the second All-Union Agricultural Exhibition (VSKhV) in 1954, that featured a series of pavilions each decorated in the style of the feature that they represent. The other famous examples are the stations of the Moscow Metro and Saint Petersburg Metro's that were built during the 1940s and 1950s are world famous for their extravagant designs and vivid decorations. In general the Stalinist architecture completely changed the way many post-war cities look, and mostly survive to this day in central avenues and public buildings.

However after the death of Stalin in 1953, the social and political changes literally turned the country over. The construction priorities were too affected and as were the architecture. In 1955, Nikita Khrushchev faced with the problem of the slow paced construction of housing, called for drastic measures to accelerate the process, and this involved developing new more mass-productive technologies and removing "decorative extras" from the buildings.
Compare the two towers of the Gagarin Square intersection, the original project was to have them be identical, but note how the "struggle with decorative extras" affected the one on the right

Effectively this put an end to the Stalinist Architecture, however as the transition was slow, most of the existing projects, that were in plan or even started to be built by 1955 were directly affected, the result was at times complete squares becoming unsymmetric.

The most famous of which took place in the post-war reconstruction of the Ukrainian capital Kiev where the planned Kreschatik avenue along with its central square Ploschad Kalinina were to form a single rich space enclosed by Stalinist constructions. However, as the buildings enclosing the latter were in process of completion, under direct orders, the architects were forced to alter them, and as a result the whole ensemble was left unfinished until only the early 1980s. In particular was Hotel Ukrayina, that was to crown the square which was originally to look similar to one of Moscow's "Seven sisters", was left as a solid shape without the top spire or any of the rich external decoration.

Nevertheless, as the buildings became more square and simple, they brought with them a new style fueled by the Space Age- functionality. The State Kremlin Palace is a merit to an earlier attempt to make a bridge between the rapidly changing styles as dictated by the state. The Ostankino Tower by Nikolai Nikitin is more of symbolism of technological advances and future.
White House in Moscow

In terms of simpler buildings, then 1960s are mostly remembered for their massive housing plans. A new typical project was developed using nothing but concrete panels to make a simple 5-story house. These Pyatietazhki became the most dominant housing constructions. Although rapidly built, the quality was in nothing compared to earlier housing and their almost identical look contributed to the grey and dull stereotype of socialist cities.

As the 1970s opened, Leonid Brezhnev allowed more choice to the architects, soon housing of varying calibers were opened. Slowly the flat blocks gained height in floors and in external decoration, large mosaics on their side became a feature. In almost all cases these were built not as standalone constructions, but part of a large estate (housing massif) that soon became a central feature of Socialist cities. Public buildings were built with varying themes. Some, like the White House of Russia made direct connections with earlier 1950s architecture, with white marble faced exterior and large bas-reliefs on the wings.
The rising skyscrapers of Moscow-City framed against the Stalinist Seven Sisters form todays skyline of the capital

Modern Russia
As the Soviet Union fell apart many of its projects were put on hold, and some cancelled altogether. However for the first time, there was no longer any control over what theme or how high a building should be. As a result, and with generally improving financial conditions, architecture blossomed in unbelieving rates. For the first time modern methods of skyscraper buildings were implemented and resulted in an ambitious business centre being built in Moscow Moscow-City. In other cases architects returned to the most successful designs, particularly Stalinist architecture which resulted in buildings like Triumph Palace in Moscow.