David L Ryan/Globe Staff

Thousands of people turned out for the open house the Red Sox hosted at Fenway Park on Thursday.

David L Ryan/Globe Staff

The Red Sox welcomed fans into the park as part of the celebration for Fenway Park's centennial.

David L Ryan/Globe Staff

Fans were able to reach out and touch the Green Monster.

David L Ryan/Globe Staff

Needham resident Brendan Mulkern, who has come to Fenway since 1949, checked out Pesky's Pole.

David L Ryan/Globe Staff

One of the most popular spots was the red seat in the bleachers that marks Ted Williams' 502-foot home run in 1946.

David L Ryan/Globe Staff

Daniel Bard did some off-day throwing amid the crowds.

David L Ryan/Globe Staff

Red Sox alumni such as Ted Lepcio and Dick Beradino, right, signed autographs for fans.

David L Ryan/Globe Staff

Fans were able to walk around the perimeter of the playing field.

David L Ryan/Globe Staff

The open house came one day before the Red Sox and Yankees met on the 100th anniversary of the park's first game.