Sixty miles east of Los Angeles, in the heart of California’s Inland Empire, the sprawling city of Riverside isn’t exactly a hotbed of tourism…except for one remarkable place. Whether you’re an architecture buff, a spa devotee or a traveler who revels in the uniquely idiosyncratic, the Mission Inn Hotel and Spa will capture your attention and hold it for days on end.

For starters, this National Historic Landmark is the country’s largest Mission Revival-style building, taking up an entire city block. But there’s more than Mission going on here—original owner and developer Frank Miller was unconstrained by consistency, building wings in differing architectural styles and adding whatever details suited his taste. That’s why the row of flying buttresses along one side are merely Gothic decorative elements, instead of serving their usual structural function. Miller built the inn in stages, finishing the final Rotunda Wing in 1931, when Riverside was thriving as the birthplace of the California citrus industry and a destination for Hollywood celebrities and other notables; the Mission Inn was where they unpacked their trunks and stayed for months at a time.

Because Miller traveled (and shopped) far and wide, the inn’s common areas are brimming with character, antiques and historical curiosities.  For example, the inn holds about half of Miller’s collection of 800 bells (many were sold off to finance the inn’s restoration), including the enormous Nanking Temple Bell, located near the entrance, as well as the oldest dated bell in Christendom, encased in glass in the lobby. (Back when Miller ran the Inn, he stuck price tags on every objet d’art in the rooms, encouraging guests to bring home souvenirs other than ashtrays.)

Given the risk of getting lost among the initially overwhelming array of towers, spiral staircases, corridors and courtyards, your best bet is to sign up for a docent-led tour from the Mission Inn Museum. You’re sure to hear the story of the custom-built Taft chair, which Frank Miller commissioned for our famously rotund 27th president. Good intentions notwithstanding, when President Taft visited, he was mightily offended by the large-scale furniture and declined to take it back to the White House.

Taft was just one of a number of presidents who enjoyed Miller’s hospitality. Some of their portraits line the lobby wall outside the wood-paneled Presidential Lounge, which serves cocktails from a menu entitled “If These Walls Could Talk.” Various martinis are named for Richard Nixon (who was married at the inn), Theodore Roosevelt, George W. Bush and Ronald Reagan. Other guests, such as Ginger Rogers, Albert Einstein and Harry Houdini, are similarly honored, though no cocktails have yet been created to mark the visits of more recent fab guests such as Miss Piggy and Leonardo DiCaprio.

Also fabulous: the inn’s pool, which is surrounded by palms and other greenery, accessorized by a large hot tub and equipped with plenty of lounge chairs and soft towels. It’s refreshing to take a dip after a workout in the fitness center, which curiously has no mirrors, but does boast two (nonworking) fireplaces, hardwood floors and stained-glass windows.

Speaking of stained glass, eight Tiffany windows grace the larger of the two chapels at the inn, which hosts about 300 weddings each year. St. Francis Chapel was built to accommodate an 18th-century Mexican altarpiece that rises from floor to ceiling in 18-karat gilded splendor. It was assembled piece by piece with wooden pegs after it was shipped to Miller in boxes. Outside the chapel, the Famous Fliers Wall pays tribute to Charles Lindbergh, John Glenn and the Tuskegee Airmen, among others. More than 150 pairs of copper wings—including a pair for Amelia Earhart, who visited the inn—decorate this International Shrine for Aviators, to whom the chapel was dedicated in 1932.

Eclectic design aside, the inn is a AAA Four Diamond property, with all the bells and whistles you’d expect. Rooms are spacious; some on the upper floors have vaulted ceilings, stained-glass windows and balconies. (Ask for a room overlooking the pool or a courtyard, and you’ll hear less noise from the surrounding downtown streets.) The grounds are gorgeous, a tableau of Spanish courtyards filled with fountains, colorful tile and palm trees; the resident pair of Brazilian macaws, Napoleon and Josephine, shriek hello to passers-by as the California sun shines on bright pink bougainvillea. And the on-site Kelly’s Spa is 7,000 square feet of indulgence, with eucalyptus steam rooms and offerings that range from a hydrating marine wrap to microdermabrasion to “Four Hands Massage” (massage a trois, anyone?).

With four restaurants (six if you count the Presidential Lounge and 54 Degrees, which serve light fare as well as drinks), plus a cupcake shop, dining options also abound. Las Campanas specializes in Mexican food, Bella Trattoria serves pizza, pasta and paninis on the plaza, and the Mission Inn Restaurant is an all-purpose eatery (breakfast alfresco is delightful). Duane’s Prime Steaks and Seafood Restaurant, named for the inn’s current owner, is the flagship. Specialties include retro favorites such as steak Diane and chateaubriand for two; the finest ingredients (Scottish Loch Duart salmon; Hokkaido scallops) are prominently featured. On Sundays, locals turn out in droves for the Champagne jazz brunch, but if you’re looking for a less frenetic experience, afternoon tea is served daily.

Outside the inn, downtown Riverside, with its art museums and architecturally significant buildings, is easily walkable. Don’t miss Tio’s Tacos. The family-owned taqueria and juice bar is surrounded by an acre of sculptures crafted from reclaimed glass and plastic bottles, encased in chicken wire and festooned with oyster shells. It’s larger than life and unexpectedly fascinating, much like the Mission Inn itself.

Traveler’s Check      

– Riverside is home to the “World’s Largest Paper Cup” (actually fashioned from concrete), which stands three stories tall in front of the former site of the Dixie Corporation’s manufacturing plant.

The Mission Inn Hotel and Spa 3649 Mission Inn Ave., Riverside, California (951-784-0300) missioninn.com