This is the Tivoli Building, which has been everything from a beer garden to a candidate's headquarters. There are also rumors that it's haunted, but I can't attest to that. Here's more information from the building's historic marker.
And the answer to the question about which book has the Tivoli on its cover is, Waiting for Spring.
You may recall some posts from earlier years showing how it's decorated for Christmas, with different rooms representing Christmas decorations from different decades, but it's worth visiting at any time of the year.
You may find more than you expect, because in addition to having elegant rooms for entertaining guests, it also has a fallout shelter in the basement, a legacy of the Cold War.
Here's a link with more information.
And, in case you're curious, Capitol Avenue extends from the Union Pacific depot to the capitol, so each building is visible from the other. How's that for city planning?
Do you recognize this? It's one of the most famous of the city's landmarks, the second Union Pacific railroad depot. Not only is it beautiful, it's also a national historic landmark. If you're curious, here's more information.
There's another reason why you might recognize the building. If you've read my Westward Winds series, you may remember that it was featured on the cover of With Autumn's Return.