IF YOU GO

Casa Mila: 9 a.m. to 8:30 p.m. and 9 to 11 p.m. daily. lapedrera.com/en/home.

Casa Batllo: 9 a.m. to 9 p.m. daily, last entrance at 8 p.m. casabatllo.es/en.

Palau de la Musica Catalana: Tours every 30 minutes, from 10 a.m. to 3:30 p.m. daily. palaumusica.cat/en.

While Casa Morera has closed since our visit, the good news is that Gaudi’s first-ever commission, Casa Vicens, which you once could see only through its wrought-iron fence, is expected to be opening to the public later this year. Stay tuned.

Bar Lobo: grupotragaluz.com/en/restaurante/bar-lobo.

Tablao Flamenco Cordobes: tablaocordobes.es/en

4 Gats: 4gats.com/en

INFO: Visit Barcelona, barcelonaturisme.com/wv3/en

Spending just one day in any unfamiliar destination is only enough time to realize that you need to spend more than a day there.

Be it a big city or a crossroads with more tumbleweeds than people, it can happen. You stop, you start looking around, and you get wind of places you really ought to see: Don’t leave without a visit to this museum or that unexplained road where the cars roll uphill.

Casa Lleo Morera is another example of Barcelona’s Modernism. Francesca Morera i Ortiz commissioned architect Lluís Domenech i Montaner to completely remodel the existing building at 35 Passeig de Gracia. It is one of several houses by top architects on the Street of Discordia, Passeig de Gracia.

But the clock is ticking. You’ve got 24 hours, that’s it. You’ll soon need to be somewhere.

We’ve all been there, right? And the reason we find ourselves in that too-short situation is that if we stay, we’ll miss … what? A cousin’s wedding? The next place on our itinerary?

Or, just maybe we’ll miss the boat. Literally.

That’s why I was in Barcelona with about 30 hours to spare. Several fellow passengers and I had arrived a day early in this city in the Catalonia region of eastern Spain, the port of embarkation for an upcoming cruise.

I’m not usually that cautious — and rarely aim to be that early — in my travel planning. But I had been to Barcelona before, several times. Just for a day, a stop among many on various cruises. I liked the place, a lot. I’d strolled with the rest of the pedestrian parade along the wide and tree-lined Rambla on my first trip, when I’d also gotten my introduction to the architect Antoni Gaudí among the mosaic lizards and serpentine terraces of Park Güell; seen the work (still) in progress of the Sagrada Familia church on my second and then third visits. Those were the musts. I figured whatever else I got to see this time would be gravy.

But I was traveling with a friend with a black belt in travel planning. Lisa takes the ball and runs with it, gleefully amassing details, deals, logistical solutions. I am grateful that she not only doesn’t mind but thrives on all this minutiae.

First she attacked the hotel requirement. She sent links of possible hotels. And a few more links. At first I had an opinion; then the hotels, which really were pretty similar, started melting together in my mind.

But I kept looking at hotels. And on one of the websites, I noticed the hotel was touting Casa Mila, yet another fabulous example of modernisme (the Catalan version of art nouveau) in the city. I clicked the link and saw a couple of pictures, and it became a must-see on this trip. Then my friend came up with three more. She started finding restaurants, and I remembered seeing the best flamenco dancers ever.

The audience at Tablao Flamenco Cordobes can experience the passion for the dance up close.

You see where this is going, right? Right past our 30 hours. But Lisa had a schedule that would fit everything in. Knowing all the ways things could derail a schedule, I enumerated a few for her, then crossed my fingers.

So here is how we attacked the city, along with the snags, the smart moves and the time potholes we avoided:

Day 1

NOON

Where: The Barcelona airport — we’re here. And already off schedule.

Snag: 45 minutes waiting for luggage.

Timesaver: Save time by spending money. We took a cab rather than a shuttle or public transportation that would include many stops and perhaps not drop us at our hotel door.

1:30 P.M.

Where: Hotel le Meridien, Barcelona.

Timesaver: Within walking distance of many sites we planned to see, as well as La Rambla.

Snag: Our room wasn’t ready. We had to change to walking shoes, etc., in the crowded lobby, deal with having luggage stored and fetched later. Plus having to hang around because our room would be ready soon.

1:45 P.M.

Where: In search of lunch. We hit the street, without a plan.

Snag: Don’t spend 20 minutes walking all over the neighborhood reading menus. If the first one looks good, go in.

Timesaver: My friend. She’s a human Zagat guide and had all the restaurants near our hotel scoped out and memorized. Two minutes from our hotel, we came upon Bar Lobo, where she stopped and said, “This is supposed to be good.” And it was.

Snag: We waited a half hour for the check. Should have sought our waitress or taken alternative action sooner.

3 P.M.

Where: Casa Mila.

Timesaver: Again, spend money to save time. Although it was close enough to walk, we took a cab.

Our timed tickets were for 3 p.m., and we just made it to this house, one of the crowning achievements of Gaudi — though he quit before it was finished because of arguments over money and design with the Mila family. It was designed as an apartment building, with the Milas occupying one of the units. Casa Mila is probably one of the most famous buildings of the modernisme style, which was not just about new aesthetic, but Catalan society’s renaissance.

Four areas of the building are open to the public, but the most famous is the roof, which, like everything else Gaudí designed, has no straight lines — even the ground undulates, like paved moguls. And all around the roof lurk strange figures vaguely resembling helmeted soldiers. These were Gaudí’s idea for hiding the too-industrial presence of stairwell covers, chimneys and ventilation shafts.

5 P.M.

Where: Back to hotel.

Timesaver: Combine sightseeing with getting to your destination. We took a route that let us walk along La Rambla for some window-shopping and people-watching, and my friend stopped off at the large local market.

9 P.M.

Where: Tablao Flamenco Cordobes.

Timesaver: Eat at the attraction. No decisions, no extra transit time.

At Flamenco Cordobes, your 79 euros (about $88 at current exchange rates) comes packaged with a preshow dinner of tapas, a glass of Sangria and dessert.

The flamenco is held in a separate small theater. You’re close enough to see the dancers’ perspiration glisten — I sat in the front row to watch the amazingly controlled footwork — and feel the thwack and thumps of their heels against the wooden stage.

Every song told a story, and while I did not know from the Catalan words what each song was about, the cadence of the music and the language of the dancers’ bodies conveyed the meaning with eloquence.

11:30 P.M.

Where: Back to Le Méridien.

Timesaver: More sightseeing on the way. We’d been curious about the Gothic Quarter, so we took a walk through that area on the way back.

The oldest part of the city, the Gothic Quarter has small, ancient buildings; little cafés; and, because people throughout Spain tend to stay up late, a lively night scene. The walk was appropriately offbeat: At one outdoor café, two diminutive Japanese women sipping drinks from 2-foot-long bendy straws; a silhouette of Marilyn Monroe on a balcony, her blowing skirt in a frozen famous ripple; Crayola-colored gelato, bright and beckoning from a still-open kiosk.

Snag: Remember to ask for a wake-up call and a follow-up 15 minutes later. You’ve got a schedule to meet.

Day 2

8 A.M.

Where: Le Meridien.

Timesaver: Wake up fast, pack fast, store luggage. Prepare for a marathon of amazing modernisme architecture.

Snag: I should have packed the night before. Wasted time.

10 A.M.

Where: Casa Morera.

Timesaver: We had planned to start out early, so we could still walk rather than take a cab.

Timesaver, Part 2: Because Casa Morera was so compact and uncrowded, we were able to see the house in less time than we’d scheduled (leave wiggle room), allowing us to have an early lunch.

Casa Morera is on the Manzana de la Discordia (The Apple of Discord), a stretch of Passeig de Gracia between Carrer Arago and Carrer Consell de Cent. This block is known for its collection of modernist buildings by four of Barcelona’s most important architects: Gaudi, Lluis Domenech i Montaner, Josep Puig i Cadafalch and Enric Sagnier.

Snag: Don’t try to see a slew of major attractions. You’ll be frustrated that you don’t have enough time and won’t be able to appreciate what you do see.

Casa Morera, built for the Morera family, was a good slow start to the day. It is small and compact and gave us a sense that someone — a family — lived there. We were also able to get a close look at the craftsmanship and detail, from the wallpaper to the intricate patterns of the wooden floors. We could appreciate the collaboration required to create these beautiful buildings; the architects of the time worked closely with the master craftsmen responsible for components like stained glass, woodwork and mosaics.

11:30 A.M.

Where: 4 Gats.

Timesaver: Eat when there’s time, not necessarily at official times. Sure it was a little early, but we were hungry.

Timesaver, Part 2: Scope out in advance not only what dining options are near your location but what is open when you’ll be there.

The cafe 4 Gats was a perfect choice for the modernisme theme, and right near our next stop, Casa Batllo. The restaurant was a knockoff of Le Chat Noir, the famous cafe in Montmartre, where Picasso and Monet and other artists of the late 19th century hung out. One of the employees at Le Chat Noir decided that his hometown of Barcelona needed something similar, so he opened 4 Gats in 1897, and it almost immediately began attracting the artsy crowd with cheap food, piano music, even Chinese puppet shows. It became a hub for modernisme with the painters, writers and architects of the time. Yes, Gaudi dined there.

1 P.M.

Where: Casa Batllo.

Timesaver: Advance tickets. They really saved us here; we waltzed right past the slow-moving line of visitors waiting in the rain.

Snag: Unfortunately, the line outside was typical of the situation within: Rooms and hallways of the casa were crowded, sometimes leading to time-wasting standstills. Bad for our timing, as well as for trying to appreciate this big building filled with Gaudi’s flourishes and details.

Along with getting advance tickets, research the best time to visit — right after opening or an hour before closing (those hours vary).

This is a masterpiece of Gaudi’s career, filled with his classical themes of nature (flowers embossed and painted on walls, door frames, ceilings) and natural forms (not a straight line anywhere).

You can visit the rooms where the Batllo family lived; the attic, which has been turned into a museum with original sketches and models from Gaudi’s studios; and (drum roll) another roof, this one more reminiscent of Park Guell, with a dragon and other serpents in the Gaudi mosaic style (broken plates and other ceramic shards are the tiles of choice).

The crowds thinned out in the staircases, which overlooked interior terraces covered in ceramics and flowery designs. I spent far too long just going up and down the stairs, taking photos from different angles.

4 P.M.

Where: Palau de la Musica Catalana.

Timesaver: The cab, again, was our only chance for being even close to schedule.

Snag: The cafeteria we had to walk through was so inviting I was tempted to stop for a coffee. My friend pulled me along.

This Palace of Music, our last stop of the marathon, was built from 1905 to 1908 by architect Domenech as a home for the Orfeo Catala choir. It’s a breathtaking homage to music and a UNESCO World Heritage Site.

Guided tours start with a video of its history and end at the concert hall, with its incredible stained-glass sunlight. Just walking in will give you goose bumps. I still get them when I think about it and the magical pink light that fills the place.

Afterward, I had just enough time for a coffee. No lingering. We had to go get our luggage and get to our ship.

We headed for the street, and I promised next time, I’d come back.

Next one-day visit, maybe I’d schedule in a whole dinner.