Warsenal just released their largest terrain piece to date.
From the website:
The interior can accommodate eight large 55mm based vehicles and still have room for a 25mm base in the center.
The roof is removable in two pieces to make the entire building accessible without moving models unnecessarily. The exterior grates are also removable and large enough to allow a 25mm base to sneak inside!
Dimensions: 13 3/16 in. x 11 5/8 in. x 6 1/8 in.
This 3mm MDF and 1.5MM acrylic piece comes unpainted and unassembled.