Famed for its interior artistic decorations. Dedicated 1906.
From the Wikipedia article:
(The entire entry is worth a read--a number of entertaining stories connected with the construction of this building and its complex.)
"The Pennsylvania State Capitol houses the chambers for the Pennsylvania House of Representatives, the Pennsylvania Senate, and the Harrisburg chambers for the Supreme Court of Pennsylvania. The Capitol contains 475 rooms and has four floors, not including a mezzanine between the first and second floors, and a basement. The bronze entrance doors of the capitol lead into the rotunda on the first floor with the grand staircase in the center. The staircase in the rotunda is an imperial staircase, similar to the one in the Palais Garnier in Paris, France. The staircase leads to the mezzanine between the first and second floors, before dividing into two staircases leading to the second floor. Edwin Austin Abbey painted four allegorical medallions around the base of the capitol dome, detailing the "four forces of civilization": Art, Justice, Science, and Religion. Four lunette murals were also painted by Abbey and "symbolize Pennsylvania's spiritual and industrial contributions to modern civilization". The lunettes are situated in the recesses of each arch in the rotunda. The rotunda is paved with tiles, hand-crafted by Henry Chapman Mercer, from the Moravian Pottery and Tile Works. Mercer produced 1,600 square feet (150 m2) of tile, which includes "377 mosaics, representing 254 scenes, artifacts, animals, birds, fish, insects, industries and workers from Pennsylvania history".