NEW YORK — Some very big, familiar pieces of New York City sports history are going on the auction block — courtesy of a baseball star.

The 10-foot high letters that spelled “Yankee Stadium” atop the original Bronx ballpark are being offered for sale at Sotheby’s on April 1. The auction house has estimated that the letters will sell for $300,000 to $600,000.

The owner is Yankee legend Reggie Jackson.

Mr. October bought the letters after the Yankees’ last game at the stadium in 2008. They had adorned the ballpark, which was built in 1923, since 1976, so they were there when Jackson hit three consecutive home runs in the sixth game of the 1977 World Series.