The details were announced by People's Democratic Reform Committee (PDRC) leader Suthep Thaugsuban.
"Twenty more stages will be set up. We'll occupy the intersections all day and night and we'll have fun on the streets.
"Anyone who wants to set up a stage can contact us so the work can be shared out," the PDRC secretary-general said on the stage of the main protest at Democracy Monument on Friday.
Mr Suthep named the 20 intersections:
3) Hua Lamphong
4) Bang Rak
6) Sam Yan
7) Phaya Thai
9) The Victory Monument
10) Siam Square
11) Lat Phrao five-way intersection
12) Din Daeng
16) Klong Toey
The Ratchadamnoen stage would be the centre for coordinating with anti-government demonstrators at other stages, he said.
Mr Suthep said a single lane will be left open for commuters's vehicles at each intersection, but the PDRC will deny access to government vehicles.
The protesters will rally in different locations of Bangkok from Sunday to Wednesday, calling on the general public to join their "shut down Bangkok" operation, he added.