A historian says many in the academic community are saddened by the actions of the Tongan government at a site in Popua.
Prime Minister 'Akilisi Pohiva is leading the development of a golf course, canals and park there.
Wendy Pond researched and wrote material on the site which the society said is of huge cultural and historical significance.
Dr Pond said the site hosted Captain Cook and his crew, is linked to the beginnings of the Tu'i Tonga dynasty and was the site of an impressive royal pigeon snaring arena estimated to have been built in 1350AD.
The Heritage Society is looking at legal action now that a 2015 petition and parliamentary promise to protect the site seems to have been ignored.
"It took us all by surprise and especially there is very great concern that the prime minister was able to order the canal and roading to be done without any reference to environmental impact assessments, without apparently any parliamentary procedure," Dr Pond said.
She backed a call the society's call for development to stop immediately.
Dr Pond said many academics visited the site because it was where a royal pigeon snaring arena once stood.
"In 1920 an archaeologist called McKern came and discovered more of these structures in the same area and then Dr Dirk Spennemann came in the 1980s and then the Tongan National Museum, with myself, carried out a survey and located the GPS of each of the seven structures," she said.