The crisp lines and clever curves of new public libraries and city halls are clean and bright. But their light good cheer can’t compare to the gravity of walking through the great glass doors of Oakland’s 1914 beaux-arts tower. The grand granite columns, the glossy marble staircases, and the great three-story rotunda show visitors and employees alike that the business of running a city really matters. Even the tackier flairs, like the glass floor in front of the mayor’s office and the odd honeycombed light fixtures in the rotunda, have been around long enough to seem sophisticated — albeit in a cocktail-lounge kind of way. The building is a relic of a time when the public first recognized that big government could help cope with big problems. The sentiment motivated the city to get Henry Hornbostel to design the tallest building in the western United States. But even in the hope of the Progressive Era, a latent suspicion of politicians might explain why they included a surprising detail: a jail on the twelfth floor.