PORTLAND – Just before City Hall Auditorium opened 90 years ago, publishing magnate Cyrus H.K. Curtis held a grand party and donated the 50-ton Kotzschmar Organ to the city.

By the early 1980s, though, the once-grand organ was in terrible condition, and city officials considered giving it up.

The organ has since been restored, and its place in Portland history will be celebrated all week during 90th anniversary festivities at the City Hall venue now known as Merrill Auditorium.

Ken Cowan, an organist from Princeton, N.J., was to have played Tuesday as part of a classical series sponsored by Friends of the Kotzschmar Organ. Lyn Larsen, of Arizona, is scheduled to perform Thursday as part of the group’s pops series.

Cowan rehearsed Monday and said that the organ’s pipes are known around the world for the depth and variety of sounds they are capable of creating.

“It’s a pleasure to come in and get to know an instrument like this,” he said. “This one takes it to a different level. It’s much more expansive in how far it goes.”

The organ’s revival represents one of the city’s great success stories, according to David Wallace, the organ’s retired curator.

“It’s at its best now since it was in the 1920s, and I have seen it at its absolute worst,” he said. “Where it was 20 years ago, I would say, ‘Yes, I am surprised it has made it to its 90th year.’ It was in such decrepit condition.”

Twenty years ago, budget concerns forced city officials to all but abandon the organ. Concerts were sparsely attended, and experts advised the city it might be wiser to give up on the Kotzschmar.

That’s when the Friends of the Kotzschmar Organ formed. Its members dedicated themselves to restoring the organ one step at a time, agreeing to raise money on behalf of the city to preserve the instrument.

Over time, they succeeded. The crowning moment came in March 1997 when Merrill Auditorium reopened after a massive $9.7 million restoration project.

The Kotzschmar was returned to its jewel status as the centerpiece of the 1,908-seat auditorium, reversing an earlier renovation that pushed it 18 feet back in favor of storage space.