More than 100 protesters were arrested in lower Manhattan on Monday during demonstrations marking the first anniversary of Occupy Wall Street, the amorphous, anti-corporate greed movement that began in New York and spread to dozens of cities last year.

Activists vowed to "shut down" Wall Street, with plans to create a human wall and block the entrance to the New York Stock Exchange. Hundreds of New York police officers were assembled early Monday in anticipation of the protests.

Dozens of officers, some on horseback, blocked off the entrance to Wall Street to prevent protesters from carrying out their stated mission. At 10 a.m., the NYPD carted off a bus full of protesters, all of them arrested earlier Monday morning. A double-decker bus of sightseers followed closely behind.

Several of the arrested protesters were in wheelchairs. (One smiled as she was loaded into a police van.) At the intersection of Broad and Water streets in the financial district, activists demonstrated in front of a police truck, raising clenched fists in its direction.

[Slideshow: Occupy Wall Street: One year later]

Matt Tucker, a protester from Cincinnati, told Yahoo News that the Occupy movement has found buildings where protesters can sleep. (Zuccotti Park, once the ground zero of the Occupy movement, is no longer an option for overnight camping.) Others slept in front of Trinity Church and Chase Bank over the weekend as part of their protest.

As is often the case with city-based demonstrations, the number of protesters who showed up Monday to mark the Occupy anniversary varied depending on who was counting. Most media outlets estimated several hundred; one protester's estimate—retweeted by Occupy Wall Street's Twitter account—was 50,000. (The tweet was immediately—and rightly—ridiculed.)

According to the New York Times' City Room blog, about 200 protesters gathered in Zuccotti at 7 a.m. A half hour later, approximately 400 protesters arrived at the Vietnam Veterans Memorial on Water Street:

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The police were also visible in large numbers throughout the area. Just after 7 a.m. four officers on scooters followed four bicyclists dressed as polar bears—to symbolize rising water tables resulting from global warming, they said—on their way to an assembly spot outside the Lower Manhattan ferry terminal.

Police who barricaded Wall Street checked IDs of employees to let them through.

A few protesters used markers to write a telephone number for legal help on their arms should anyone arrested need it. A small band of demonstrators outside the church performed in a drum line. One held a sign that read: "Sorry, Wall Street is Closed Today for Deconstruction."

Some Occupy protesters played drums and marched around behind barricades, even as they were blocked from entering Wall Street. Other splinter groups performed "mic checks" (creating a people's microphone where listeners repeat a speaker's words so others farther away could hear) in the lobbies of major banks, including J.P. Morgan Chase, Citibank and the Bank of America.

The anniversary demonstrations began on Sunday with a concert in Foley Square featuring Rage Against the Machine guitarist Tom Morello.