Eta Carinae
The Eta Carina nebula is the heart of the Carina Molecular Complex. It's the 'last' of multiple structures in the Complex, whereas other clusters and nebulae lie 'in front' of it when approaching from Sol. It's some thousand light years wide and 9,000 light years from Sol.
There are many T Tauri stars lying closely together and the occasional massive O type star, including the supermassive Eta Carinae system. The death of stars is a common sight in and around as there are some neutron stars and also a couple of black holes in the vicinity. These violent deaths in the past have contributed to the nebula's immense gas columns.