"Basically, it's one of the earliest schools," said Thomas Lim, architectural branch chief for the state's Historic Preservation Division.

Although Central initially opened in the palace structure — which had previously housed Honolulu High School — the buildings that have been recognized are more recent, built after Keoua Hale was razed because of termite damage. The existing buildings date back to 1926.

School officials learned it had been placed on the national register just in time for an assembly celebrating Ke'elikolani's birthday Wednesday. Students paid respect to the princess with song, cards, poetry and lei.

According to custodian Roger Aquino, the school was actually placed on the national register a year ago, but no one informed the school.

In fact, the school might still be in the dark if Aquino had not asked the state Historic Preservation Division about the status of the school's federal nomination from 1994.

Aquino received a brief letter this week confirming that the downtown school had been added to the list on Feb. 11, 2004.

He noted that there's no presentation or even a certificate to recognize the school's status, but told the students to "be proud and be loud" because "we're on the national level."

Ke'elikolani, a descendant of Kamehameha and governor of the Island of Hawai'i, was the Kingdom of Hawai'i's largest landowner. Upon her death in 1883, she left her estate to her cousin Bernice Pauahi Bishop, whose husband, Charles Bishop, sold Keoua Hale to the state with the understanding it was to be used for educational purposes.

Principal Melissa Trew said the designation will mean the school should always be mindful of its history before making decisions.

"We've been recognized as a building of value that we need to protect and we need to understand its place in history in Hawai'i and what it means to the tradition of our students and the tradition of our culture here," she said.

When the school opened as Central Junior High School in 1928, it was one of five new public secondary schools established to follow the Mainland trend of creating more mid-level schools. It was also one of the first schools to require an English-language exam for entrance.

While several other secondary schools of similar age have been placed on the national register, Central is "the only remaining secondary school in Hawai'i in its original building," Lim said.