French astronaut Leopold Eyharts announced its arrival. "Beautiful work," radioed Mission Control.
It was an exhausting daylong affair that took more time than expected.
The grand finale -- the actual attachment of the 23-foot, 14-ton lab that was ferried up by Atlantis -- took place at the end of an extra-long spacewalk by Rex Walheim and Stanley Love. The astronauts shouted and cheered when the lab reached its destination.
Germany's recovering astronaut, Hans Schlegel, was stuck inside the whole time. He was supposed to float outside with Walheim to help with Columbus' hookup, but got sick following last week's liftoff and was replaced by Love.
The last-minute switch in crew prompted NASA to delay Columbus' installation by a day and lengthen Atlantis' space station visit.
U.S. and European space officials have refused to divulge the illness.
Even though two Americans ended up doing all the outside work, it was still a momentous occasion for the European Space Agency, which waited years to see Columbus fly. The lab was supposed to go up in 1992 to commemorate the 500th anniversary of the sailing of Christopher Columbus, but space station and then shuttle problems delayed everything.
As Columbus was lifted by a robot arm out of Atlantis, astronaut Daniel Tani reported: "Columbus has started its trip to the New World."
Columbus expanded the almost 10-year-old space station to eight rooms. It attached directly to the Harmony compartment that arrived last fall. Another of Harmony's docking ports will be occupied by Japan's new lab once it launches in the spring.
The 10 astronauts aboard the linked shuttle and station will wait until Tuesday before entering Columbus. Additional work on the lab's exterior will be performed during a second spacewalk on Wednesday and a third on Friday. Unless flight surgeons object, Schlegel is expected to make Wednesday's spacewalk, along with Walheim.
During Monday's outing, Walheim and Love ended up falling behind. They removed protective covers from Columbus and plugged in a grappling pin for the robot arm, and completed some other chores although not everything. They stopped to rest as the spacewalk dragged on; it lasted eight hours, 1 1/2 hours longer than planned.
"Man, you guys have done an amazing job," shuttle commander Stephen Frick told the weary spacewalkers at the six-hour mark. "We're looking out our window here at Columbus, about halfway there."
Operating the space station's robot arm -- and hoisting Columbus -- was astronaut Leland Melvin, a former wide receiver and NFL draft pick.