The LEGO Factory theme, active from 2005 to 2008, included the Modular Buildings subtheme, which introduced highly detailed, interconnected building sets. The 10190 Market Street, released in 2007, is a key set in this subtheme. Designed by a LEGO fan, this set features a three-story building with a market on the ground floor and residential spaces above. It contains 1,248 pieces and includes three minifigures. Market Street is compatible with other modular buildings, allowing for the creation of expansive, interconnected cityscapes. This set helped lay the groundwork for the popular LEGO Modular Buildings series that followed.
The Factory theme was introduced in 2005 and was powered by LEGO Digital Designer (LDD), a free LEGO virtual building program for the computer. Using the LDD people could design their own 3-D LEGO virtual model, and submit it for purchase using the LEGO Shop-at-home. The Factory platform was also designed to allow users to view and purchase other users custom creations. Once ordered, these Factory sets came in special packaging that showed the model as well as all included LEGO elements needed to build the design.
During Factory's beta phase, The LEGO Group sponsored a contest where people could submit their designs, in which 8,000 designs were submitted and people and LEGO Master Model Builders voted on the top models. Ten models were selected to become real LEGO sets available exclusively through LEGO Shop-at-Home.