The central feature of the Old House is a tall gabled log structure housing the lobby, dominated by a deep, steeply-pitching shingled roof. The Old House uses load-bearing log lower exterior walls with a log pole interior framework supporting seven stories, six of which are the roof structure. The upper gable walls are of milled lumber framing with shingle sheathing. The front slope of the shingled roof is accented by shed and gabled dormers, some of which are purely decorative. Both interior and exterior framing is supported by twisted or curved branches, giving the entire structure a strongly rustic air. There are two levels of balconies, the lower encircling the lobby and the upper on two sides. Stairs climb from the second balcony to a platform in the framing known as the "Crow's Nest" which once was used by musicians to entertain guests, then on to the crown of the gable above the lobby floor. The entire structure is crowned by a roof walk that once held searchlights to illuminate Old Faithful Geyser at night. The original guest wings are stories tall on either side of the lobby. It is anchored to the ground by a rhyolite foundation that extends to the first floor window sills.