The ceremonies marked the 70th anniversary of the day when mass executions started in Moscow's Butovo district.
The executions on August 8, 1937, signaled the start of a wave of purges that killed an estimated 40 million people.
A large wooden cross has been erected in Butovo, at the site where mass executions and burials of political prisoners took place.
The cross was made in a northern Russian monastery on the Solovetsky Islands, which served as a Soviet prison camp in the 1930s.
(compiled from agency reports)