Demonstrators marched by the federal building and police in riot gear lined Downtown corners as protests began in earnest yesterday, just before leaders from the world's largest economies arrive for the G-20 Summit.

More than 100 HIV/AIDS activists rallied under the David L. Lawrence Convention Center, where the summit will be held, calling for universal access to anti-retroviral medication.

About 35 protesters on the corner of Liberty Avenue and Grant Street spoke out against police harassment and intimidation, claiming that Pittsburgh has been transformed into a police state.

And about 25 protesters allied with the Three Rivers Climate Convergence marched from the Art Institute to the federal courthouse, calling for cleaner energy and decrying coal power.

Each protest was matched by an extensive police presence, as clusters of state troopers rode through the streets on motorcycles and unmarked police vans trailed demonstrators. When the coal protesters stopped to sing and chant in PPG Plaza, they were told to leave the premises -- which are private property -- by growing number of police officers, who formed a line 19 abreast.

Protesters came from around the country, some hopping on buses from nearby neighborhoods, others riding for hours from New York City or Austin, Texas.

It took Grady Minnis two weeks to get to Pittsburgh from Asheville, N.C.

He rode his bicycle, he said, raising awareness along the way about mountaintop removal caused by coal mining, which has deeply affected his home state.

The Rev. Jeffrey Jordan of ACT UP Philadelphia left the city at 7 a.m. yesterday to arrive in time for the 2 p.m. HIV/AIDS march.

"It's very important," said Rev. Jordan, who is HIV positive.

"With the help of God and my medicine, I have a sustained life," he said. "I feel like the same privileges I have, people all over the world should have."

The HIV/AIDS march was sponsored by a coalition of groups, including ACT UP Philadelphia, New Voices Pittsburgh, the New York City AIDS Housing Network and more.

It was modeled after a funeral procession, symbolizing the deaths organizers said will be caused by a shortfall of funds to fight HIV/AIDS.

Bearing a black cardboard coffin and dressed in black, protesters carried black and white signs shaped like tombstones. On stickers and in chants, they demanded that President Barack Obama deliver the $50 billion in HIV/AIDS funding he promised while campaigning for the presidency.

Mary Adams, an HIV/AIDS nurse from Rochester, N.Y., said she has watched even the sickest of her patients grow healthier and continue their lives with proper care and access to medication.

"And at the same time," she said, "people around the world have access to no medicines, not even antibiotics."

"How powerful the pharmaceutical lobbies are that they have basically blocked the production of AIDS medications in Africa," said Khafre Abif, an activist from North Versailles.