The house was alive.

Or so it felt, standing just about anywhere in Casa Batllo, a private home designed by Catalonia's most famous native son, the architect Antoni Gaudi. On the outside, mask-shaped balcony fixtures with cutout eyes appraised the stream of visitors entering below. A staircase railing's asymmetrical bulge gripped the curves of my palm on ascent. Gazing down at the patio, with its reflective tiles in staggered shades of blue and slatted-glass shutters, was like being lulled by the sight of ocean waves rippling in the sun.

I could have sworn that the low wall on the roof terrace, covered in broken multicolored tiles that resembled scales, was undulating like a snake crossing the road, though I hadn't yet had a drop of cava that day. If the marching brooms from "The Sorcerer's Apprentice" or singing teapot from "Beauty and the Beast" had come prancing along, I wouldn't have been a bit surprised.

So it goes with Gaudi immersion. When you wander through his color-drenched, shape-shifting spaces, alone, with no timetable or companion chatter to ground you, your imagination can run almost as wild as his did.

Even though they stick out like wacky aunts in a family reunion photo, Gaudi buildings are integral to the urban landscape of Barcelona, Catalonia's lively capital on the Mediterranean Sea. Just like the city's well dressed, casually friendly people you bump elbows with on the main pedestrian drag, La Rambla, they are equal parts earthy and urbane.

Born in 1852 into a family of coppersmiths, young Antoni Gaudi was a math whiz and loved nature, both qualities that would come in handy later. A master of modernism, he was also influenced by art nouveau and Gothicism. Now exalted, he fell in and out of favor during the 20th century, particularly among minimalists, to whom his work was a garish, baroque nightmare.

No matter your degree of interest or expertise in architecture, if you can remember just two things about Gaudi, you can have fun applying them to each site you visit. First, as surreal and whimsical as his symbolism can seem, most of his work is modeled after natural forms, especially the shapes of plants and animals (like Casa Batllo's undulating snake wall, actually a dragon's spine). Second, he loved to incorporate function -- like that oddly shaped staircase railing -- into his fantasies. On that same roof terrace, the chimneys and ventilation shafts are disguised by what look like giant jesters' crowns.

It's easy to understand why people think, mistakenly, that the word "gaudy" comes from Gaudi. Visiting more than two sites in one day can overwhelm the eyes -- not to mention leaving you convinced that Gaudi was, as rumored, a big fan of hallucinogenic mushrooms.

Actually, that rumor got started because he was fond of making finials in the form of capped toadstools. Regardless, letting Gaudi be your guide is unavoidably, delightfully trippy. For a warm architectural buzz rather than the dizzying, disconcerting high of his Basilica of the Sagrada Familia, it's best to spread your visits over several days, with plenty of time for tapas in between.

Of four can't-miss Gaudi destinations in Barcelona, try to save the most jaw-dropping -- Sagrada Familia -- for last, to get the most out of it. Park Güell is a nice open-air option for easing into Gaudi style. Two residential buildings, Casa Batllo and Casa Milà, are a fitting combo, just three blocks apart on the same street.

Park Güell

Built between 1900 and 1914, the park is named for a primary Gaudi patron, wealthy industrialist Eusebi Güell (pronounced gway). Originally envisioned as a garden city, it emulates an English-style garden in its layout, though it's hard to picture an English garden entrance adorned by a lizardlike dragon sculpture covered in Gaudi's signature trencadís, mosaics made with broken tiles of varying shapes and sizes. The park's cheesiest feature, it is also the most popular. Elsewhere there's plenty to explore, including viaducts and a classic Greek marketplace and square, gussied up with such Gaudi-isms as zodiac symbols.

Casa Batllo

Pronounced BAHd-yoh, with just a hint of "d," this five-story formerly private home has been open to the public for only the past 10 years. Rounded shapes on the rostrum of the facade could be meant to represent anything from bones to lava to those ever-present mushrooms.

A remodeling job commissioned in 1904, the house was once occupied by a single rich family. I imagined mopey teens stumbling sleep- ily from bed to fetch breakfast, inured to Gaudi's ergonomic chairs and the rest of their amazing environs.

Casa Milà

Nicknamed "La Pedrera," or "The Quarry," this six-story apartment building finished in 1912 has a rippling stone facade that makes it look woozy, but in fact is supported by an ingenious system of pillars and beams. The 200 windows in its two roof-to-ground patio wells help bring light to every corner of the massive building. It also features very futuristic, for the time, private elevators for residents and an underground car park.

Sagrada Familia

Asked when his masterpiece would be finished, Gaudi replied that his client, God, was in no hurry (so the story goes). A good thing, because the most recognizable object towering above the Barcelona skyline is still a work in progress, 130 years after construction began.

The Sagrada Familia ("Holy Family"), a Roman Catholic church, is nearly 560 feet tall. From afar, its spires look like taper candles softened by heat, like something out of Dr. Seuss' Whoville (Seuss, aka Theodor Geisel, was a Gaudi admirer), or, as one young American visitor was overheard to say, "a bunch of skinny ice-cream cones upside down."

George Orwell found it "hideous." Louis Sullivan felt the opposite, calling it "spirit symbolized in stone." Regardless of your aesthetic sensibility, you'd have to be dead not to be awe-struck.

The basilica's three grand facades, the Nativity, the Passion and the Glory, tell virtually the entire story of the New Testament in sculpture. Many of its ornamental details also serve a purpose, such as the apse gargoyles, modeled after reptiles and amphibians, which drain excess water from the roof.

With Spain's economy tanking, it's fortunate that the funding of Sagrada's construction is entirely private. The latest estimate for completion is 2026, the centennial of Gaudi's death. In 2010, Pope Benedict consecrated it as a minor basilica.

A devout Catholic -- he was on his way home from attending mass when he was struck and killed by a tram at age 73 -- Gaudi has been suggested for sainthood by many a fellow Spaniard. He hasn't been canonized, and probably never will be. But his work is testament to the possibility that greatness doesn't have to be pretentious, Technicolor-mosaic lizards notwithstanding. It's also a perfect complement to Barcelona's greatest appeal, a sophisticated yet embraceable culture.

Kristin Tillotson • 612-673-7046