Calgarians are being invited to commemorate what the city is calling "the worst natural disaster in modern history" at a special ceremony on June 20.

Last year the city was hit hard by floodwaters that spilled the banks of the Bow and Elbow rivers.

More than 80,000 Calgarians were forced to flee their homes in the aftermath.

"This is an opportunity for sombre reflection on the floods that struck Calgary and the continued impact on many in our community,” said Mayor Naheed Nenshi. “It’s important to acknowledge the flood anniversary, while we continue to move onward, working together to rebuild and recover.”

The city says the aim of the ceremony, featuring special guests and dignitaries, is to reflect on the impact the disaster had on the city. It will also feature the unveiling of a legacy display and the Kids’ Flood Art Call Out from earlier this year.

The event will kick off at 8:30 a.m. at the Calgary Municipal Building atrium downtown.

“Everyone is welcome,” said Nenshi. “Every Calgarian showed great compassion, resilience and strength in the face of immense adversity, and we should honour that together.”

However, the city says seating is limited and will be provided on a first-come, first-served basis.