Helen Morgan, Liberal Democrat MP for North Shropshire, made the comments after meeting with campaigners from Hands off Old Oswestry Hillfort (HOOOH), the group seeking to protect the ancient site.
The Iron Age hillfort is one of the best preserved in the country, but has been the focus of an ongoing battle against plans to build housing on the land around the historic settlement.
The latest application for 83 homes on land off Whittington Road was turned down in March – but not over concerns about the impact on the fort.
Planning officers instead chose to refuse Galliers Homes' proposal on the grounds of its effect on local roads, drainage and the environment.
Now Mrs Morgan, who was elected in a shock by-election victory in December, has spoken of the need to protect the historic monument – and to make the most of the opportunities it offers, both for local people and tourists.
She said: "It is such an important monument and part of our heritage, we should be trying to preserve its separation from the town so people can appreciate it properly.
"It is a site of national significance, that is why there have been such high profile supporters.
"We have a duty to preserve it for future generations to understand and appreciate our history. It is something we should be proud of and trying to look after."
During a visit to the site, Mrs Morgan was shown around by an expert archaeologist.
Mrs Morgan said the opportunity was there for the town of Oswestry, and the wider area to bring more visitors to the county.
"With the opening of the Cambrian Railway – that is a real win for the town – it is a local tourist attraction," she said.
"The hillfort is another important part of the town's history and if we want people to visit and spend their money here we need to be looking after these sites."
Mrs Morgan said that those wanting to protect the hillfort could push further for an 'exclusion zone' for planning around the historic site.
She said: "I think the campaign team would like to see some sort of exclusion zone around it for development so people do not submit planning applications for that spot.
"There is a concern that once you allow one development in that space there would be 'in-fill' in the rest of the green space between the fort and the road."