Barcelona

The main sites are those designed by Antoni Gaudi. Take a tour for a day and be sure to go inside Sagrada Familia that is a huge cathedral still growing.

Watch out for pickpockets, Barcelona is the pickpocket capital of Europe. Men wear a money belt, women carry a pack safe purse.

One day is really very tight for Barcelona, whose main sights are a bit spread out and require timed tickets. Make it 2 days if you can!

Besides the Gaudí buildings, the old town (Barri Gótic) and adjacent El Born neighborhood are worth exploring, with the cathedral, the Plaça Reial, and a huge warren of winding streets where it is very easy to get lost. Avoid getting lost in El Raval, on the other side of Las Ramblas, though.

I really enjoyed the Cathedral much more than anything else in Barcelona and yes pickpockets are out in force. My brother had pocket picked only losing an expired metro ticket. He was also targeted by three girls who shoved a petition at him to sign, it was so obvious. Funny thing was that I intervened and he is the one in the family with a black belt but I guess I am the loud mouth that scared them away. You can still enjoy the city just concentrate on your surroundings.

Rick lists his top sightseeing recommendations for many major cities on this very website:

Rick's picks in Barcelona Click on "At a Glance"

I don't have many quibbles with Rick's list. A major one is inclusion of the Ramblas. It's a shopping street with a lot of people walking along it, quite a few of whom are pickpockets. Why is that an important sight in a city like Barcelona with numerous good museums and lots of wackadoodle architecture? You are highly likely to end up walking along part of the Ramblas anyway; there's certainly no reason to make a special effort to go there.

La Sagrada Familia has to be considered the top sight in the city. Tickets aren't cheap, and you need to buy one online in advance. I don't know how much in advance, because I haven't been to LSF since 2016. Casa Mila, Casa Batllo, Parc Guell and the Picasso Museum also call for buying (timed) tickets ahead of time, because the ticket lines are massive. For the lovely Palau de la Musica Catalana, designed by a different modernist architect, the English tours can sell out, so that's yet another visit that requires pre-planning.

You should expect all of the above except the Palau de la Musica Catalana to be utterly mobbed; if one of them isn't, you are extremely lucky. Plan to visit one of them first thing in the morning on each day you're in the city; that way, you'll at least walk into a building that doesn't already have a bunch of people from earlier entry cohorts inside. You'll probably soon have a sardine-like experience nonetheless. Think about the likelihood of sub-optimal viewing conditions when considering how many of those rather high-priced places to visit.

Because of the need for timed tickets at so many places, it's very difficult to see Barcelona quickly. How will you know when to book entry for the second stop, the third, etc.?

The Recinte Modernista Sant Pau site is still relatively undiscovered, though designed by the same architect as the Palau de la Musica Catalana. You don't need to prebook Sant Pau; just show and buy a ticket, which will be quite a bit less expensive than some other options. This is my second disagreement with Rick's list: Sant Pau should be on it.

Barcelona is very popular and the big-name sights will be packed, but it's a lovely city. To have only one day there (or even two days) would be a shame.

If you have never been to BCN you are cutting it way to short but sometimes that's all you got. I was there last summer and this is may recommendation. Start the day at Sagrada Famila, do buy ticked online and in advanced or you may be disappointed. Allow yourself 2 hours in Sagrada Familia. The San Pau Hospital is near by, but I would skip it, unless you want to do a quick dash through it. I would then taxi to the top of Passeig the Gracia and walk down to Plaza de Cataluña and admire some of the most recognizable Gaudi and other modernist buildings. At leasurely pace this takes about 1-1.5 hours). From Plaza de Cataluña I would enter the Gothic quarter toward the Cathedral and surrounding important buildings. Make a walking plan (I followed RS audio tour), it is easy to get disoriented. This is also 1.5-2 hours. After you hit the main spots you wish to see step back into the Rambla and visit the Mercado Boqueria. Take a break and have some food. It will be expensive but very good. After that you can stroll down the Rambla and get a feel for the city and its vibrancy. Walk down to the Colon Monument and past it to get a feel of the city's ocean front. From here walk to the down the pier to the Montjuic Fonicular station and take it to the castle atop the hill and across the harbour. Spend some time exploring the castle grounds and then take a taxi to the Mirador Barcelona in front of the Museum Nat'l dArt and the walk down passing the Magic fountain to the Plaza de España. You should be exhausted at this point. Go to your hotel take a break, change and head out for dinner at a restaurant that fits your interests. Happy travels