The Fourth Mainland Bridge is a 38 km-long bridge project by the Government of Lagos State, Nigeria, connecting Lagos Island through Langbasa (Lekki) and Baiyeku (Ikorodu) across the Lagos Lagoon to Itamaga, in Ikorodu. The bridge is a 2 × 4 lane carriageway cross-sectional road with permission for BRT Lane and future road contractions. Upon completion, it is expected to become the second-longest Bridge in Africa, featuring 3 toll plazas, 9 interchanges, a 4.5 km Lagoon Bridge, and an eco-friendly environment, amongst other added features. The idea was conceptualized by the government of Lagos State's former governor, Bola Tinubu. Construction was planned to commence in 2017, 50 years after the state's establishment and 26 years after the completion of the Third Mainland Bridge by the former military President Ibrahim Babangida. While it was initially expected to be completed by 2019, construction has still not started as of November 2023. The project was estimated to cost the state approximately ₦844 billion in the 2017 budget. In September 2020, the Lagos State Government proposed another sum of $2.2 billion for the construction. On the other hand, approximately 800 houses are expected to be demolished during the bridge's construction, significantly fewer than the 4,000 houses designated for demolition under the previous construction plan, which was realigned afterward. In April 2021, there were 6 bidders for the US$2.5 billion project. By December, the preferred bidder would be known.