The monuments at Green-Wood Cemetery are undergoing their annual sprucing up at the hands of an expert preservationist from overseas.

Thorsten Moewes has been power washing grave markers and mausoleums for 25 years. He works for the German company, Karcher, which has sponsored free cleanups for monuments around the world for the last 35 years.

Karcher's past projects have included Mount Rushmore here in the states and the Brandenburg Gate in Berlin.

Green-Wood Cemetery President Richard Moylan says he's proud the historic graveyard has made that list.

"It's a great honor," he says.

Karcher's process involves using no chemicals -- just water heated to exactly 310 degrees. The low-pressure power washing does not damage the monuments, officials say.

The company will also donate equipment to Green-Wood and teach its current preservationists their techniques.

The Karcher team will clean three monuments over six days before departing.