(CNN) The departure lounge at Brussels Airport partially reopened Sunday for the first time since suicide bombers attacked on March 22, about six weeks ago. The bombers detonated explosives near the check-in desks, killing 16 people and gutting the building.
The airport at large reopened on a limited basis in early April.
The city remains on edge as police continue to hunt down those linked to the attack at the airport or the same-day deadly explosion at a Brussels metro station. The Maelbeek station, where 20 people were killed, reopened April 25.
ISIS has claimed credit for the carnage.
Here are some of the most significant twists and turns the investigation has taken and what's ahead.
There have been dozens of raids across Belgium that have netted evidence and suspects, some who have been charged. Operations have been widespread: in France, Germany, Italy and the Netherlands.
* One of those recently charged is Ossama Krayem, a Swedish citizen who had already been charged in connection with the Brussels attacks and was formally accused of involvement in the November terror attacks in Paris. In late April, a prosecutor called Krayem "omnipresent" during the planning of both attacks. Police said he traveld to Belgium from Germany in October in a car rented by Salah Abdeslam, the Paris attacks suspect who eluded authorities for months until his March arrest in Belgium.
* Law enforcement has said Abdeslam was a key player in the Paris attacks that killed 130 people. On March 18, he was captured after a gunbattle with police. He has claimed a minor role in the Paris attacks.
* Also in April, terror suspect Mohamed Abrini was arrested in Brussels. He also has been tied to the Paris attacks through surveillance video and DNA. Authorities are questioning him about the Brussels airport attack.
* Terrorists who attacked Brussels initially planned to strike again in France but changed their minds as investigators closed in, the Belgium prosecutor said in early April. They changed their minds when French investigators appeared to be moving very quickly toward figuring out who was behind the Paris killings, and that's when the terrorists decided to hit Brussels.
* In February, a laptop recovered by investigators in Brussels included a list of targets in Paris such as the financial district and a Catholic association, according to TV news station BFM. Over the past several months, many more pieces of evidence have been recovered at various locations, including explosives, equipment to make explosives and an ISIS flag.
Identifying Brussels bombing victims has been a long and difficult process. The victims spanned 40 nationalities.
Their stories and backgrounds reveal the widespread ache that terrorism leaves in its wake.
At Brussels Airport on Sunday there was a brief opening ceremony before the departure hall began business.
"Sunday is an important day in the recovery of Brussels Airport. The doors of the departure hall to passengers will open again. The fact that this is possible in less than 40 days after the attacks is without any doubt a technical and operational tour de force that took an enormous effort of hundreds of people," said Arnaud Feist, CEO of Brussels Airport Company.
Feist called the moment an important turning point for the entire airport community and for Belgium. "For many of them it will be a difficult moment, but they can count on the support of our large airport family," he said.
Feist noted that in the immediate few months, "It will be very important to rebuild the image of our country abroad."
The airport is able to serve about 80% of the passengers it served before the attacks but Feist said it hopes to get fully up to pace by mid-June. Passengers are advised to allow at least three hours before their flights.