In the span of one day, Moscow went from the brutality of violent, massive street clashes between young, mostly male protesters and riot police to the pomp and circumstance of Vladimir Putin's inauguration, held in the gilded Kremlin State Palace.

file photo Putin's third inauguration was a lavish event, with more than 2,000 guests and a banquet that reportedly cost more than $800,000 to prepare. Yet despite the almost royal pageantry, Putin's return to office failed to bring closure to the cycle of protests that posed one of the most severe challenges to his authority since 2000 and grew significantly more violent on the eve of his return to the Kremlin.

In a speech televised nationally on six Russian channels, Putin called for national unity in the days ahead. "We will achieve our aims if we are a single, united people, if we hold our fatherland dear, strengthen Russian democracy, constitutional rights and freedoms," he said.

Those TV channels have also ensured that most of the country won't see what began on Sunday evening and carried over through the next day ­ violent clashes between riot police and irate protesters, more than 650 detained in the course of a day, and dozens from both sides hospitalized. The devolution of the "March of Millions" demonstration planned by Left Front leader Sergei Udaltsov showed that future opposition protests are unlikely to be as well planned and as quiet as those in the months following the December elections.

On the square, glass bottles and flares elegantly arced into the ranks of riot police, who faced off with young, mostly male demonstrators, many of whom wore masks and balaclavas. Against the backdrop of the Kremlin, police would muster and charge, swinging batons and punching with plastic knuckle guards before dragging several protesters back to waiting police wagons and reforming into tight ranks. Several times a mysterious gas ­ possibly pepper spray or tear gas ­ sent protesters scattering in fits of coughing. The police later blamed protesters for releasing the substance.

The ebb and flow repeated for hours. Occasionally riot officers would stray too far into the crowd and fall mercy to the kicks and punches of the demonstrators. Cheers rose through the evening as heavy police helmets were tossed into the nearby river.

In a reference to Ukraine's "Orange Revolution," several opposition groups set up tents on Bolotnaya Square that had been smuggled in past a police checkpoint. "We'll stay here as long as we can," said Nadezhda Mityushkina, a member of the non-systemic Solidarnost movement's leadership. "But we don't think that will be for very long."

The protest started off as many of the others opposed to electoral fraud and Putin's return to the Kremlin had ­ a peaceful march through the city center to a square situated across the river from the Kremlin's walls. The mood was positive due to a turnout that far exceeded the permit for 5,000 people (estimates of the number of protesters vary widely, from the police's 8,000 to the protest leaders' claims of more than 150,000).

Zhenya, a 19 year-old Moscow State University law student, said he wore a surgical mask ­ similar to those that some of the most aggressive protesters on the square were later sporting -- to protect his identity from possible reprisals to his career. "Everyone in the universities, even the professors, are all against Putin," he claimed.

In contrast with earlier demonstrations, many of the protesters had also come in from outside of the capital, where support for Putin is markedly greater than in Moscow. Igor Nesterov, a middle-aged demonstrator from Nizhny Novgorod, said he had travelled in after a business trip to Vladimir to join the protests. "I was thinking: 'why on earth am I coming to Moscow,'" he said as the column neared Bolotnaya square. "But I decided that it was my duty."

The mood soured at the entrance to the square, where the protesters ran into a wall of thousands of riot police who refused entry to the square. It was not clear who started the violence ­ a colorful mix of anarchists, provocateurs, or riot police have all been suggested ­ but once protesters started getting detained, the rally became defined by its violent, and not its peaceful, nature.

The police brutally and efficiently cleared the square several hours later. In official statements, the government played hard-line: Interfax announced that the young men who had been detained and hadn't fulfilled their military service were being conscripted. Dmitry Peskov, a Putin spokesman famed for winding up opponents, said he thought the police took it too easy on the demonstrators.

On Monday, the cycle of protests and arrests continued, though on a smaller scale. Two restaurants popular among opposition planners and journalists were raided by riot police, who reportedly arrested diners at will. In the evening, more than a thousand demonstrators had come together in the center of the city, singing songs in an unlikely gathering that resembled the "Occupy Wall Street" protests more than the free-for-all on Bolotnaya Square the day before.

"The inauguration of a new president is always a new era in the history of a country," said outgoing President Dmitry Medvedev in his remarks at the inauguration ceremony on Monday. For Putin, an opposition that is tenaciously holding on even after the inauguration and has now flirted with violence could be the most unwelcome element in his new term as president.