(CNN) -- Former Chicago Mayor Richard M. Daley remained hospitalized early Sunday morning, two days after he fell ill.
Daley, 71, was taken by ambulance to Northwestern Memorial Hospital in Chicago on Friday evening after he returned from a business trip to Arizona, the hospital said.
Daley is in the hospital's intensive care unit for evaluation -- with his family by his side, the hospital said.
A former state senator and county prosecutor, Daley was elected mayor in 1989, to complete the term of the late Harold Washington. He was re-elected over and over until he decided to not run for reelection in 2011.
In all, he served a record 22 years as Chicago's mayor. His father, Richard J. Daley, also served as the city's mayor.
President Barack Obama's former Chief of Staff, Rahm Emanuel, succeeded the younger Daley.
Since leaving public office, Daley has kept busy, including speaking engagements and as special counsel at a law firm.