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The dome of the Idaho State Capitol rises 208 feet into the Boise skyline, a classical architectural form prominent among the city’s modern multi-story buildings and landscape’s rolling foothills. The Renaissance Revival Capitol is Idaho’s most significant historic structure and a building that reflects city and state political, social, and economic history. Over 100 years since conception, the Capitol continues to function as the seat of Idaho’s state government, currently housing the executive and legislative branches and numerous state offices which occupy much of the approximately 190,000 square feet of usable space. The Capitol and its surrounding grounds occupy two blocks of the urban grid, providing grounds proportional to the building’s roughly 328-foot north and south facades and its depth of approximately 170 feet established by the east/west axis. The south facade offers the principal entrance at the culmination of a vehicular approach to the building that cuts centrally through the city as part of a grand procession leading to the Capitol. The siting of the building enhances its authoritative scale and strongly classical design. Although the use of traditional architectural form is drawn from various historic epochs, the materials used in realizing the design draw upon local resources. Composed of locally quarried stone, the sandstone exterior resonates the dusty light auburn hues of Boise’s surrounding foothills, adapting the Capitol’s civic symbolism to serve the people and land of Idaho.
Construction took place in two separate campaigns with work on the central portion beginning in 1905. As constructed in this first phase, the central portion consisted of the rotunda and dome, the north wing housing the Supreme Court, and the offices positioned on either side of the abbreviated east and west corridors. The formal portico, centered on the approximate 168-foot south facade of the central portion, shelters the building’s main entrance at the second floor atop a steep set of steps with a porte-cochere beneath. Set upon a granite base course, the balance of the structure is built of locally-quarried blocks of sandstone. Above the granite base are five courses of rusticated sandstone shaped to suggest stacked logs in the style of early log structures of Idaho’s pioneering era. The centrally-positioned terra cotta dome is situated above a colonnade that encircles the dome’s supporting drum. Supported by steel structural members that are concealed beneath the terra cotta, the dome is topped with a traditional illuminated lantern—a perch for the bronze eagle which serves as a symbol of both Idaho’s aspirations as a State and its allegiance to the larger democracy. In 1912, the central portion was completed after seven years of construction, and building occupants moved into their offices in the proud new statehouse.
Plans for building expansion were put into effect in 1919 when funds were secured for the construction of the east and west wings. Completed the following year, and flanking either side of the central portion, the new wings provided additional office space for the numerous agencies housed in the building. Additionally, elegantly-appointed grand meeting chambers were provided for both the Senate and House of Representatives. Each space was illuminated by skylights and capped on the exterior by symmetrical half-domes. Adding roughly 80 feet to each end of the building, the east and west wings followed the precedent of the central portion in adhering to the four-floor elevation accented by classical colonnades and entablature. Grand stairs on both the east and west ends of the building provided monumental access to the wings. The same local sandstone used in the construction of the central portion and quarried from the nearby state-owned Table Rock Quarry was again used on the wings.