Mayors from New Castles around the world gathered Monday at Slippery Rock University for the third International New Castle Summit of the World.

Environmental initiatives are the focus of the three-day event in Pennsylvania, according to a news release from the state Department of Environmental Protection. Delegates from Japan, Germany, Switzerland, England, Ireland, Scotland, Wales, Australia, Canada, Jamaica, Wyoming, Delaware, Maine, Colorado, Washington, Oklahoma, New Hampshire and Kentucky were invited to the event.

The cities of New Castle, Pa., and New Castle, Ind., co-sponsored the event, a news release from the New Castle Network of Cities said. Events will also take place in Indiana with education as the focus of discussion, the release said.

"We are very proud to be hosting this year's New Castle Summit of the World," New Castle Mayor Tim Fulkerson said in a news release. "We are especially pleased because this year's theme is the environment, and we in Pennsylvania have so much to share with the world in what we have done to improve our environment. We are anxious for our colleagues in other states and countries to learn about what we're doing here."

David E. Hess, secretary of the DEP, talked to delegates at Slippery Rock University about Pennsylvania's environmental initiatives, including recycling mine reclamation and Growing Greener, designed to fund environmental programs.

Delegates were to tour sites in New Castle today.

There are about 35 New Castles in the United States and 50 Newcastles found in the English-speaking world, according to the book "Newcastles of the World United."

The first international summit was held in Shinshiro, Japan, in 1998, and the second summit was held in 2000 in Neuchatel, Switzerland.