PENSACOLA, Fla. (AP) — A National Park Service team of historic preservation experts has turned its attention to Battery San Antonio at Pensacola Naval Air Station.

The Maryland-based team transitioned to the project earlier this week after doing major repairs at Fort Pickens on Gulf Islands National Seashore.

The more than 230-year-old, Spanish-built Battery San Antonio presents unique challenges for the preservationists because of its age.

"This is the oldest part of the fort system in this area. It is actually listed as a historic landmark, the highest rating there is," said Eric Hutchinson, a masonry expert who will be working on the battery's walls for the next several weeks.

The team is repairing cracks in the stucco walls, which form the fort's perimeter. Preservationist Elizabeth Price carefully applied layers of stucco to a crack in a wall last month. She used a trowel to gently place the specially blended stucco in a long section of wall underneath a drain.

Hutchinson said the areas underneath the drains frequently crack because of the water that runs down the wall. The team is adding metal extensions to the drains to help move the water away from the fort's walls.

The original drains would have been terracotta. Those drains cracked and broke over time and PVC pipe was placed inside the drains decades ago to help move water away from the fort. Metal drain extensions should solve the problem, Hutchinson said.

"Sometimes you have to resolve an issue using modern materials because it is the best solution and helps prevent further deterioration," he said.

The team plans to repair about 20 large cracks in the fort's walls.

Preservationist Curtis Ward worked inside the fort last month.

Ward pressure washed mold and moss from the walls and applied a biological agent to help keep plants from growing into the walls.

Ward, who did similar work at Fort Pickens, said Battery San Antonio actually appears to be in better shape, even though it was built about a half century earlier.

The battery at Pensacola Naval Air Station appears to have been better maintained through the years, he said.

"This fort is interesting because it has that Spanish mission feel. Also, it's older and was built by the Spanish. That history makes it interesting to me," Ward said as he prepared to power wash a section of the interior wall.

Hutchinson said he was surprised by some of the decorative flourishes that the Spanish added to the fort. There is ornate scroll work over some of the doors and parts of the upper stucco walls were scored to make them appear as if they were made of brick.

Especially impressive — the brick tunnels that connect sections of the old Spanish battery with Fort Barrancas.

"The vaulted tunnels are an amazing example of precision masonry," he said.

Hutchinson, Ward and the other preservationists are based at the National Park Service's Historic Preservation Training Center in Frederick, Maryland. The team traverses the country to repair historically significant park service sites.

According to information provided by the park service, Battery San Antonio dates to the British colonial era. Bernardo de Galvez stormed the British Royal Navy redoubt in 1781 and the Spanish began building Battery San Antonio at the site.

Completed in 1797, it is the third oldest standing fortification in Florida and among the oldest in the United States.

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Information from: Pensacola (Fla.) News Journal, http://www.pensacolanewsjournal.com