The most beautiful building I have ever seen is Tabatabayis House  built around 1880 in Kashan, Iran.

The house is renowned for its intricate stone reliefs, fine stucco and wonderful mirror and stained-glass work. The house consists of three sections: the andaruni (the internal area where family members lived), the biruni (external area used for entertaining and housing guests) and the khadame (servants' quarters). These are set around four courtyards, the largest of which boasts a fountain pool. From mid-afternoon (depending on the month), sunlight and stained glass combine to bathe some rooms in brilliant colour.

Read more about Iran architectural attractions.

Hi Courtney!! I am a big fan of the genius Antonio Gaudi and all his masterpieces. The fashionable stone building La Pedrera or Casa Mila is one of my favorite because of its undulating, living forms façade. The attic and the roof are a beauty and the series of catenary arches amaze me every time I watch the pictures taken. This is not an ordinary, or common building, nothing looks like assembled or built, instead it looks like Gaudi plopped it as a hug mountain of slippery clay then dug his thumbs and fingers into it to make windows, doors, balconies, everything!!

Here some pics to show what I mean.

Saludos from Costa Rica!!

My favorite is Blue Mosque in Istanbul

I've never seen a more beautiful stained glass skylight than the one in Barcelona's Palau de la Música Catalana. Definitely go on a sunny day! 

Basílica de la Sagrada Família in Barcelona, so interesting, and the more time you take to learn about it, and look at the detail, the more beautiful and interesting it becomes.  Enjoy!

Oh boy... There is so much to choose from! One of the most incredible buildings is the Parlament in the wonderful city of Budapest.

Second place goes to my hometown Cologne and the amazing Cologne Cathedral. Such a beauty!

Another kind of building (because its really old and I'm not sure it qualifies as a building) is the temple The Bayon in Cambodia. It looks like its from another planet!

The Strater Hotel in Durango is one of the most beautiful buildings in the world. It looks a bit like a wedding cake.

I'd say definitely the Cologne Cathedral. You walk out of the train station there it is larger than any building I've ever seen and the detail is just amazing.

Sheikh Lotfollah Mosque in Isfahan. 

Basílica de la Sagrada Família!!!

As an architecture junkie it is so hard to single any out with one exception. Basílica de la Sagrada Família, a Gaudi creation. It is truly an architectural experience.

Taj Mahal mesmerized me and so did Ciudad de las Artes y las Ciencias

I still love the Alhambra, kinda of touristy, but unique. The Pantheon in Rome, nearly 200 yrs old. Much less known is the "New" cathedral in Coventry UK. it is built beside the bombed out (WWII) old cathedral.

Sydney Opera House Such a gorgeous building inside and out. The fact that it's right on the harbor only adds to its beauty.

The Taj Mahal in Agra, India. This is a building you can watch for hours, under different angles, and different light. Its symmetry is probably a big part of what makes it so beautiful. All that pale marble, as well as the inlaid stones and arabic calligraphy that decorate it, are also very elegant.

The Canadian Museum of History in Ottawa Canada designed by Douglas Cardinal. I wish I had a picture but you can Google it.

Tough question!

I think my favorites are the Pantheon in Rome, the Palau de la Música Catalana in Barcelona, Hagia Sophia Istanbul Old City, Museo Guggenheim Bilbao, Teatro Colón, Robie House...

I could go on forever!

Hi Courtney, 

Great question that got me thinking...I can't decide between my two favourites: The Pantheon in Rome - because it's one of the oldest structures of Ancient Rome and is a feat of great building and design and anytime I visit I really feel part of history. I also love the Sydney Opera House because of its elegance, beauty and location.