Modular Buildings is a series of Lego building toy sets introduced in 2007, with new sets usually being released annually. Created in response to feedback and suggestions from the Adult Fans of Lego (AFOL) and Teen Fans of Lego (TFOL) communities, the sets in this series are generally intended for more advanced builders. Most sets contain more than 2,000 total pieces and make use of unorthodox building techniques not usually utilized in previous official Lego sets. In contrast to most Lego sets aimed at children and adolescents, the suggested age of most sets in the Modular Buildings series is 16 years or older. The Modular Buildings sets have been received with positive reviews and are considered by Lego designers and fans as "toys for adults".