When the Union Grounds opened on May 15, 1862 for baseball in Williamsburg, Brooklyn, it became the first enclosed baseball grounds in America. Three clubs called the field on the corner of Marcy Avenue and Rutledge Street home; however, the Eckford of Brooklyn were the most famous tenant. They played more games than any other club that year (7) and won the "national" championship, repeating the feat in 1863. During that two year period, the Eckfords won 22 straight matches which was the longest undefeated and untied streak to date. In the late 1860s, they were one of the pioneering professional clubs, although probably second to Mutual of New York at the home park. In its final season, Eckford entered the second championship of the National Association, the first professional baseball league in America, so it is considered a major league club by those who count the NA as a major league.