Looking up Nu'uanu Avenue, he pictures the lava rock quarries used to build the Nippu Jiji Building (home to a Japanese newspaper) in 1896. On the Fort Street Mall, he reflects on the stark, missionary culture prevalent when Father Damien de Veuster was ordained at the Our Lady of Peace Cathedral in 1864.

Warren, an associate professor of geography at Hawai'i Pacific University, is no idle daydreamer.

He says walking the streets and surveying the historic buildings is how students in his human geography class will best appreciate the influence of politics, economics and art on Hawai'i's skyline.

"What does that (building) tell us about the social, political and economic realities of the people of those times," said Warren, who leads walking tours of downtown as part of his classes. "I use this built environment as a window into discovering what was going on in Hawai'i during these time frames. A visual text that can be read almost like a book."

Warren, standing in front of the old Blaisdell Hotel building, prefers architecture that includes a Hawaiian sense of place. Deborah Booker • The Honolulu Advertiser

From his classroom on Fort Street Mall, Warren takes his students on a detailed tour providing information about the various architectural styles downtown, from the Mediterranean-style old Honolulu Police Station (1931) on Merchant Street to the modern "glass box" skyscrapers of the modern business district.

"One of the traditions of geography is the cultural landscape," he said. "The visual evidence of human existence. What do people do to the surface of the Earth that is visible? What does that tell us about those people? I use downtown Honolulu because we are right here. I want to use something that is literally right on our doorstep."

Architectural tours are popular with tourists in many cities, from London to Chicago, Prague to San Francisco, but Warren said his tours are not only to entertain, but help to wake students up to the world around them.

HPU student Kekoa McClellan, 20, took the class last year to fill his geography requirement and now recommends the class to others.

"We went down every street and he talks about every single building and the historical significance of each, even down to the sidewalks," McClellan said. "We all learned something. That is the way every class should be."

Warren doesn't take students inside the buildings so as not to disturb tenants, but he doesn't mind going into the former Blaisdell Hotel, which is now used by HPU, to show off the "birdcage" elevator, which requires an operator and is the only one of its type still in existence in Hawai'i.

"You don't go in and just push the button," Warren says inside the gilded wrought-iron cage. "Somebody takes you up to the floor you want to go."

The current somebody is Javier Fombellia, who has been working there for a year and has been up and down so many times he has lost count. He effortlessly pushed the brass handle that silently lifts and lowers the elevator.

Fombellia said the building reminds him of buildings in his native Cuba, which he left in 1967.

Warren has created a guide that divides the architectural periods in Honolulu into eight groups. He doesn't have any one favorite era, but laments the modern period with "glass box" buildings that have been built from New York to Tokyo to Los Angeles. He prefers architecture that includes a Hawaiian sense of place.

"A lot of old Honolulu was torn down," he said, "with the new, modernistic skyscrapers that replaced older buildings, and we did lose a lot of treasures. In the early '60s, late '70s there was the peak of head-long development and almost total disregard for anything that was older."

Where the Topa Financial Center now stands between Merchant Street and Nimitz Highway is where the old 1840s courthouse stood.

"They said we can't use it and it was torn down without much protest," he said.

"When you look at the Alexander & Baldwin building (on Bishop Street) there is really nothing else like it in the world. It's architecture that is quite unique to Hawai'i. That building plus the immigration building on Ala Moana Boulevard represent this fusion between east and west that is really unique to the world. Those sorts of things are definitely worth preserving."