As Toronto welcomes the world, much of the city is closing its doors.

With the G20 summit just three weeks away, the downtown core is already beginning to resemble a ghost town. Fear of potentially violent protests and the traffic nightmare that will likely spring from a billion-dollar security operation have prompted several downtown institutions to take pre-emptive action, shutting down operations voluntarily before circumstances force their hand.

Yesterday, Mirvish Productions called off performances of the musicals Rock of Ages and Mamma Mia! for the week of June 21-27 due to security concerns in the theatre district, the only time they have had to cancel a show other than in the blackout of 2003.

Via Rail announced that its trains will not stop in the city on June 26 or 27, but will instead board passengers from suburban stations.

"Everyone says this is a wonderful opportunity to showcase the city. But what are they going to showcase?" asked John Karastamatis, a spokesperson for Mirvish Productions.

The decision to call off the two Mirvish shows came after much consultation with police. While the Integrated Security Unit was helpful, Mr. Karastamatis said, they could not provide enough information to ensure the theatre patrons would be able to get into the district.

"We heard there will be major delays on the King Street car line. We heard people won't be able to even stop and let people out of cars. We called police and they said that may or may not be true," Mr. Karastamatis said. "It's very frustrating because the information seems to change day to day."

Mirvish has struck a deal with its union that approximately 600 performers and staff will not be paid for the dark week, but will receive other concessions, which he would not detail.

But the theatre still expects to suffer a substantial loss. The cancelled shows will result in 28,000 empty seats, and the building costs and security must still be maintained.

Mirvish is also closing the parking lot beneath the Princess of Wales theatre because so few people are expected to be downtown during the weekend.

Via Rail announced its trains will start and stop at suburban stations to avoid Union Station from June 24 through 27, and will operate on a weekend schedule because of "extremely low advance ticket sales."

"Due to the proximity of Union Station to the main meeting location," said Via president and CEO Marc Laliberté, "we know that there will be major congestion, making access for our customers very difficult."

FirstEnergy, a Calgary investment bank, has cancelled a conferences scheduled for Toronto Four Seasons on June 24 because not enough people planned to attend. And the Factory Theatre, located at Bathurst and Adelaide, will close its 2009/2010 season a week earlybecause of the G20.

This week's announced G20 closings are in addition to recent changes to the Blue Jays schedule, which moved planned home games to Philadelphia, and the shutdown of the entire University of Toronto campus. The Ontario Legislature also announced it would be boarding up its windows.

Meaghan Gray, of the Integrated Security Unit, would not comment on how the closings would affect the city's image when the summit begins, and said police have provided as much information as they can.

"We've met regularly with almost all of the downtown stakeholders and given them as much information as we can," she said. "They've chosen to make decisions that are entirely up to them and in the best interest of their business. We respect and support that."

Not everyone, however, is packing up and leaving town.

GO Transit plans to operate its regularly scheduled service, although it is hiring more security guards for the week of the summit.

"We are advising travellers that there will be delays to travel times and disruptions to our service due to factors out of our control," said spokeswoman Vanessa Thomas.

And the scheduled Toronto FC match against Galaxy on June 26 will go ahead as planned.

"We always have issues to deal with here, whether it be road closures around Exhibition or what have you," said spokeswoman Michelle Lissel. "All our fans know what's going on."

Toronto Pearson International Airport will also be operating as usual, although a travel advisory warning visitors of an "increased police and military presence.

Brad Ross, a spokesperson for the TTC, said that some buses will be rerouted to avoid Union Station and Queens Quay and that riders should expect delays.

The Pittsburgh transit authority saw a 70-per-cent reduction in ridership during their G20 summit last September, costing it about $500,000, but Mr. Ross said he does not expect transit lines to be empty.

"People still need to get to work," he said. "And it will certainly be easier to take transit than it will to drive."

Producer David Mirvish said he is trying to see the big picture when it comes to the closings affecting the city.

"I feel a little sorry that I'm going to lose some money, but I think we're doing what is best in terms of being a good host. People have to make something of a sacrifice in order for this meeting to take place," he said. "If the result is that these people are able to make some decisions that benefit the world, than it will be worth it. The onus shifts from us to them."

Mr. Mirvish said he hopes world leaders come back another time and visit High Park and the Canadian Opera Company.

"There's lots to do in this city when they're not so busy," he said.