The phrase "a remarkable condition" is correct and usable in written English.
It can be used to describe a situation or state that is noteworthy or exceptional in some way.
Example: "The patient was diagnosed with a remarkable condition that had never been seen before in medical history."
Alternatives: "an extraordinary situation" or "a notable state".
Dissociative identity disorder, previously called multiple personality disorder, is a rare and remarkable condition in which two or more distinct and independent personalities develop in a single individual.
Archaeologists found a silver-gilt crozier (a kind of staff of office) and a jewelled ring in remarkable condition.
"The newly raised gun carriage is a very important find and in remarkable condition" said Charles Trollope, a leading expert in 17th century naval artillery.
"The letter and envelope are in remarkable condition, with an impeccable provenance, and they represent a truly unique opportunity to own the finest example of its genre in existence.
In February 2009, it was made public that in late 2007 the wreck of the ship was discovered "in remarkable condition" during an underwater survey between Italy and Algeria for the GALSI gas pipeline.
The longhouses near Lake Ozette had been buried suddenly by a mudslide sometime around 1560, preserving their contents in such remarkable condition that the site is often referred to as the American Pompeii.
Built in the late 18th century by Sultan Sidi Mohammed Ben Abdullah (and designed by a French engineer he had captured), the town ramparts are in remarkable condition, with superb bronze cannons, some dark green with burnished patina and Portuguese crests; booty from long-ago wars.
The historic Aggie Grey's Hotel, built in 1933 and made famous as a club for servicemen during World War II, has been kept in remarkable condition.
Many, he said, are in remarkable condition, from the smallest powder jars to the largest vases.
