The pages of history continue to turn for the U.S. Navy's oldest commissioned warship, USS Constitution. She will soon exit the historic Dry Dock One at Charlestown Navy Yard, Boston National Historical Park in Charlestown, Massachusetts.

The undefeated Constitution, affectionately called "Old Ironsides," entered dry dock for the first time in more than 20 years on May 18, 2015 for a planned, multi-year, $12 to $15 million restoration. The sea is expected to once again meet her hull, July 23.

Since Old Ironsides entered dry dock, repair facilities in the Navy Yard have been filled with the sounds of saws, grinders and other machinery as teams of contractors and Constitution Sailors work side-by-side to repair and preserve the nearly 220-year-old ship. Sawdust and wood chips lined the floor as a modern-day carpenter's mate carved and smoothed wood that replaced old damaged parts of the ship, for example, just one step in the painstaking work of bringing Constitution back to her glory.

A cadre of craftsmen from the Naval History and Heritage Command's Maintenance Detachment Boston had the delicate job of melding new tools and modern-day technology with extensive knowledge of 18th-century shipbuilding techniques to complete the restoration.

"We do work with modern tools, but we still use some of the old methods: The hull planks are still pinned through the deck, but we use hydraulics and pneumatics to pull them out," said Det. Boston's director, Richard Moore.

Of all the repairs, the most daunting task was replacing the copper sheathing on her hull that gives Old Ironsides her nickname. The copper was last replaced in 1995. The new restoration saw 3,400 new sheets of copper added to protect her hull below the waterline.

Additionally, craftsmen replaced lower hull planking and caulking, along with select deck beams, and continued on-going efforts to preserve and repair the ship's rigging, upper masts and yard arms.

Constitution started her service to the U.S. Navy Oct. 21, 1797. Since 1907, the ship has been on display in Charlestown, her decks open to the public. An estimated 300,000 people visit her every year, carefully guided by her active-duty Sailors. According to Naval History and Heritage Command Director Sam Cox, this mission serves an important purpose.

"Her mission today is to preserve and promote U.S. Navy heritage by sharing the history of Old Ironsides and the stories of the men and women who have faithfully served with distinction on the warship's decks for 217 years," Cox said when Constitution first entered dry dock. "When a visitor sets foot on the deck of USS Constitution, he or she is making contact with the beginnings of the U.S. Navy, a navy that has kept the sea lanes free for more than 200 years. Keeping her ready to do so is incredibly important.

"Constitution was the product of unique American ingenuity," Cox continued. "At a time when the U.S. Navy was outnumbered by the great European navies, Constitution was designed to outgun anything she couldn't outrun, and outrun anything she couldn't out-gun. Coupled with great captains and well-trained and disciplined Sailors, that is why she was undefeated."

Editor's Note: Check out All Hand Magazine on social media as we bring you footage of this important and historic day.

Read about the Sailors of USS Constitution below:

Sailing into History - Sailors of USS Constitution Part 1
Boatswain's Mate 1st Class William Sanchez

Boots to Roots - Sailors of the USS Constitution - Part 2
Seaman Ashley Maldonado

The Face of the Navy - Sailors of the USS Constitution Part 3
Gunner's Mate 2nd Class Randall King