The contract to build the South Dakota State Capitol was signed in 1905, with construction beginning in 1907. The architectural plans from the Montana State Capitol were adopted as the base plan for the design with some modifications made. The cornerstone was laid in June of 1908. Construction was completed on June 25, 1910 with the formal dedication occuring on June 30, 1910. An additional annex was added to the north side of the original structure in 1932 to add needed additional office space. On the east grounds of the Capitol was a deep draw that contained mostly eroded gumbo soil and weeds. This 5 acre area was an eyesore and in 1913 a project was completed that turned this area into the modern day "Capitol Lake" that includes an artesian well dug to feed into the lake and a dam along one side of the lake. Originally a manmade island was part of the lake, but this was later turned into a peninsula. In 1914 an extensive landscaping project was began to plant trees and shrubs, many of which still reside in the present day grounds around the Capitol.