A Climate Camp protest took place at Heathrow in 2007
Heathrow Airport, the Bank of England and the Treasury are among 22 sites which will be targeted by climate change activists on Wednesday.
The Climate Camp group said about 1,000 people would gather across central London before a "mass swoop" on sites to be revealed by text messages.
Earlier, activists refused to reveal to police the sites where they hope people will gather for the week-long protest.
The Metropolitan Police said it was preparing a "proportionate response".
The campaign group has not yet revealed where it plans to set up its central camp, with members saying they "just don't trust" the police.
The Met had urged the activists to reveal the location to help it police the protest.
Climate Camp organised a protest in Kingsnorth in Kent in 2008 and a week-long campsite near Heathrow Airport in west London in August 2007 to protest against plans for expansion.
This year campaigners plan to target 12 organisations which they call the "dirty dozen".
The list includes the Department for Energy and Climate Change, the Department for Business Innovation and Skills, the Department for Transport, the Stock Exchange, carbon trading firm Climate Exchange and Heathrow Airport.
A spokesman for Climate Camp said: "The targets have been chosen because of their enormous impact on climate change because of their promotion of failed market logic like carbon trading.
"Many of these targets can expect a visit over the course of the Climate Camp."
Protest organisers said activists would participate in a "mass swoop", just after noon on Wednesday, on an open space in central London and would "build the site", which will have shops, toilets and daily events.
A spokeswoman for the Met said: "We are aware of the information posted on their website and a proportionate police response will be in place."