A giant dog house is designed for the type of dog that eats you out of house and home! We're talking about Great Danes, Irish Wolfhounds, Mastiffs, Scottish Deerhound, Saint Bernards, and the like.
Some dog owners prefer to buy as large a dog house as they can find and then place a smaller shelter inside the house. The interior shelter might be a barrel or perhaps a dog box. The advantage of this approach is that the larger structure provides primary protection from the elements while the smaller structure provides a cozy den for your pet - with good body heat retention. During the warmer months, the interior shelter can easily be removed if desired.
Actual dimensions of a giant dog house from Blythe Wood Works: 60"L x 40"W x 58"H. Floor size 57" x 37", Door opening 18"W x 32"H. (They also make a "godzilla" dog house if you can imagine that...)