Police in Russia have blocked an unauthorised protest against President Vladimir Putin.
The demonstrators - of the Other Russia grouping - were trying to reach Pushkin Square in central Moscow.
In small groups holding flags aloft, they began converging.
But about 9,000 police had been deployed to block their access routes.
Faced with an impenetrable wall of determination - this woman shows the policeman a copy of her rights enshrined in the Russian constitution.
Moments later, clashes began as demonstrators tried to get through.
At least 170 were arrested.
Among those detained, former chess world champion Gary Kasparov - one of the leaders of the protest.
But journalists were not spared either.