Baltimore removed two pieces of its skywalk to spur development at Charles Center, a downtown mix of shops, restaurants and entertainment. In both cases, the links were rarely used and viewed as a public nuisance.

Four years ago, the city eliminated a span that connected the downtown convention center to Mechanic Theatre, an important performance venue at Charles Center.

"It was creating sort of a dark spot in front of the major buildings, and it was a good haven for vagrants. Nobody used it," says Shubroto Bose, architect with Baltimore Development Corp. "By taking it down, it made the (nearby) plaza much more open and pleasant." Another link was removed more than a decade ago for similar reasons.

Most of Baltimore's skywalk system remains. It links seven blocks from Charles Center to the convention center, major hotels and Inner Harbor, a massive riverfront development.

Milwaukee's skywalk system connects eight blocks with two links over the Milwaukee River through downtown.

In the mid-'80s the city set aside money to connect another 4-5 blocks on the eastern edge of downtown, but Mayor John O. Norquist killed those plans when he took office in 1988.

"The mayor hasn't been a big fan of a fully completed skywalk system," says Jon Wellhoefer, president of the private, nonprofit Milwaukee Redevelopment Corp.

Despite Norquist's opposition to an expanded system, he has supported additions over his past 15 years in office.

Despite some criticism that the system robs street life, the skywalk remains popular with downtown office workers, tourists and convention goers, according to Vanessa Welter, spokesperson for the Greater Milwaukee Convention & Visitors Bureau.

Downtown Minneapolis' massive skywalk spans nearly 7 miles and 75 bridges and is widely regarded as one of the nation's most successful. It links the Target Center, a convention center, hundreds of shops and restaurants and 3,500 of 6,000 downtown hotel rooms.

New links are constantly added to the maze, including an addition last November linking a vibrant redevelopment known as Block E with Hard Rock Cafe, GameWorks, a theater and hotel.

The city and private investors share ownership of the skywalk, depending on location. As in Cincinnati, when a link runs through a private building, the owner of that building is responsible for maintenance, heating and air-conditioning of the glass-enclosed passages. The city must maintain links through publicly owned buildings, such as the convention center.

Building owners also provide their own security forces because police rarely patrol the above-ground walkways.