The waters in Venice's main canal turned fluorescent green on Sunday in the area near the Rialto bridge and authorities are seeking to trace the cause, Italy's fire department said.

The Rialto Bridge in 2005. Courtesy of Wikimedia Commons. The work at Saint Mark’s, in contrast, is part of continuous maintenance at the 11th-century Byzantine-style church.

FILE - In this file photo dated Tuesday, March 27, 2018, a view of the Rialto bridge, in Venice, Italy. The recent devastating Notre Dame fire in Paris was a warning bell that all of Europe needs to ...