Finland Plays the Soviet Union

When western filmmakers were unable or unwilling to film in the Soviet Union, they often filmed in Finland for a variety of reasons (this is somewhat ironic, considering that Finland fought a civil war/war of independence and then 2 more wars against the Soviet Union).  Reasons for filming in Finland included:

• Finland was a free society in which obtaining permission to film was much easier than in the Soviet Union, especially in cases where the Soviet Union was portrayed in a negative light or was the source of the film's villains.
• Finland's landscape and climate was similar to much of the Soviet Union (the northern Russian part at least), making a good stand-in for many parts of northern Russia.
• Similarly, due to Finland being a part of the Russian Empire for over a century before independence, the architecture in many of the cities (especially public buildings) bore a strong resemblance to the architecture of many Russian cities, making it relatively easy for cities like Helsinki to stand in for cities like Moscow or St. Petersburg.

Here are the films I have seen that have used Finland to stand in for the Soviet Union.  Keep in mind that this is not meant to be an exhaustive list of every film that did this, just a list of the ones I've seen.

Reds (1981):
A biopic of John Reed (Warren Beatty), Helsinki was used as a stand-in for St.Petersburg/Petrograd/Leningrad (yes, they're all the same city...), and Moscow as well.  One of the most well-known sequences is a montage of John rekindling his relationship with Louise Bryant (Diane Keaton) while they're reporting about the Russian Revolution, all scored to The Internationale.  During this sequence, Helsinki's Senate Square is featured prominently:

Later on in the film, Finland is, surprisingly enough, used to actually depict Finland!

 
Finland was not the only country used to substitute countries, however; Spain was used as a stand-in for Central Asia, and the scenes taking place in France were in fact filmed in Britain (as were several interior shots, including those taking place in the Winter Palace).   In total, Reds was filmed in 5 different countries.

Gorky Park (1983):
When 3 dead bodies are found in Moscow's Gorky Park with their faces and fingertips sliced off, it's up to Moscow Militia Chief Investigator Arkady Renko (William Hurt) to find out who they were, who killed them, and why, in a work that's part mystery, part glimpse into everyday Soviet life. An adaptation of the novel by Martin Cruz Smith, Gorky Park used Helsinki as a stand-in for Moscow.  For example, Helsinki Technical School played the role of Moscow Militia Headquarters:

...while Kaisaniemi Park stood in for the titular park:

Elsewhere in the film, efforts to make Helsinki look more like Moscow included:

• Painting a giant mural of Lenin on the side of a building:
  
• Placing Russian-language signage everywhere:
  
• And having lots of extras dressed in Soviet military uniforms during street/crowd scenes:
  

The Fourth Protocol (1987):
Based on the book by Frederick Forsyth, the KGB is launching a plan to destabilize Britain in the hopes of both severing the Anglo-American alliance and driving Britain out of NATO.  They plan to do this by smuggling in an atom bomb piece by piece, then having it detonate next to a US Air Force base where American aircraft with nuclear warheads are stationed.  Because this operation was so top-secret, there are only a handful of very senior government officials involved.  The operation is handled almost entirely from the various dachas in the countryside belonging to those same officials.  In film terms, this means that there is no need to dress up Helsinki or any other Finnish city to look like Moscow; instead, the forests in Finland substitute for the forests outside of Moscow.

 

That said, I do have a film that was filmed in Helsinki and which actually takes place in Helsinki: Jim Jarmusch's Night on Earth (1991).  A series of vignettes depicting five different taxi drivers in five different cities (going west to east), the Helsinki segment follows the earlier Los Angeles, New York, Paris, and Rome segments.  It's interesting to see this after having watched the other works, so now you can see Senate Square without crowds of revolutionaries:

It's also interesting to see a residential neighborhood and realize that the same style of buildings had earlier stood in for a Moscow neighborhood:
From Gorky Park:

 

From Night on Earth: