After years of delays, Major League Baseball's Chicago Cubs on Monday launched the first phase of a multi-year $575-million program to renovate and expand Wrigley Field, one of the league's oldest ballparks. 

Demolition work is proceeding despite a lawsuit filed in August against the City of Chicago and its Landmarks Commission by owners of several surrounding buildings. The suit, filed in Cook County Circuit Courts, asks a judge to throw out a July decision by the commission to allow construction of seven outfield signs, which owners contend will block the views of clubs that view games from their rooftops. 

Although the Cubs hold a long-term contract owners to maintain rooftop views in exchange for 17% of club earnings, the suit targets a 2004 city ordinance specifying protected features of Wrigley, including  “the unenclosed, open-air character, the exposed structural system and the generally uninterrupted 'sweep' and contour of the grandstand and bleachers.”

The suit does not name the Cubs, and it is unclear how it will effect the club's renovation plans. Initial work involves expansion of left and right field bleachers, an undertaking requiring demolition and reconstruction left and right field walls and bleacher seats. 

Crews also will lay foundations for outfield signage and a 2,400-sq-ft video scoreboard, and excavate a pair of parking lots to accommodate new below-grade spaces, including a 30,000-sq-ft- clubhouse.

Crews are performing work during a six-month window between baseball seasons. The Cubs anticipate it will take four years to complete the program, which includes construction of $200 million in office, hospitality and retail space on parcels surrounding the 100-year-old structure.