Floor cubes must be placed immediately after their auction. At the start of the game, each of the 3 development rows is limited to 4 buildings — from the street to the river. Floor cubes are placed number side up on the square development lots.
The first Floor cube in each row must be placed in the development lot adjacent to the street. Players may build in any of the 3 rows. Additional Floor cubes in a row must be placed on top of or adjacent to another Floor cube in the same row. Empty
development lots between buildings in the same row are not allowed. Players cannot build on or past a Building Permit.
To place a Floor cube on top of an existing Floor cube, the cube being placed must have a lower number than the cube directly below it. In this way, there can be a maximum of 6 Floor cubes in one square development lot. Players may look at the value of any of the Floor cubes in any of the buildings. The 5 development lots with white dirt may only have a total of 1 Floor cube.
Players may not place a Floor cube on top of a Rooftop.
If a player places the first Floor cube of any color on the board, that player takes the matching Company Certificate and places it in front of them for all to see. A player may own multiple Company Certificates. At the end of the game, the player earns either positive or negative points for each building with a Floor cube of this color directly underneath a Rooftop.