Some TMNT stuff really isn't for little kids.

Idw first lair

In the IDW continuity, the first lair is the New York City sewer location where Splinter, Leonardo, Michelangelo and Donatello lived for the first sixteen months after their mutation. Raphael joined them after fifteen months, and it became his home for a brief time afterwards.

This first lair was—compared to the second—more of a typical sewer location, which Splinter and the Turtles had furnished with appliances and furniture. However, they were forced to evacuate this lair when it was invaded by M.O.U.S.E.R.S. controlled by Old Hob, which not only compromised the secret location of their home but also wrecked the structure and everything within it. The Turtles did not return to this lair, and instead took up temporary residence in Second Time Around building.