I nominate A Roof With A View for retirement. It appears to have been a specific event with no apparent plans for recurrence and, as such, should be an archived event, as suggested generally in the comments here.

If archiving/retirement is undesirable, A Roof With A View could possibly be changed to a more flexible task than an event if reworded, but the current description is limiting: "SFZero will lead the way up. At the top we will provide a collaborative art project to work on." Unless we are all SFZero and players in other cities organize such projects... but still, this wording gives the impression of a specific organized event ("we will provide").

This task/event had 15 collaborators/participants and looked like a success, but it has not yet been repeated since its lone appearance in March 2006. The players went to the top of a hotel (at Laguna & Geary, yes?) in San Francisco's Japantown, where they made and tossed paper airplanes from the notes they wrote to strangers. (My favorite note from the proof: "It's not litter now that you've picked it up. It's a souvenir. Today is a good day.") Participants also made audio recordings describing what they saw from the roof, and as someone who wasn't there and isn't familiar with the area, it was fun to listen to the off-the-cuff descriptions and different takes on the view.

What can we collectively learn? Events are cool. Events are fun. Proofs like the March one are fantastic for players who couldn't be there.

But especially as the number of tasks increases as the game grows, perhaps event-specific tasks should be marshalled into their own category or subcategory and then archived if not intended to be recurring events.