Haussmann, Haussmann and again Haussmann. We owe this 19th century architect the main big boulevards of Paris, its straight avenues starting at the Place de l’Etoile, its freestone buildings with grey slate roofs. When he called him in 1853 to renovate Paris, Napoléon III hoped to better control the flow of traffic, encourage economic growth, and make the city "revolution-proof" by making it harder to build barricades. Haussmann accomplished all this by tearing up many of the old, twisting streets and dilapidated apartment houses, and replacing them with the wide, tree-lined boulevards and expansive gardens which Paris is famous for today. Haussmann was so criticized at that time that he was finally fired in 1870. The only remains of the old Paris are now concentrated in the very centre of the city: Le Marais, L’île de la cite and l’île Saint-Louis, and the Latin quarter. Also, Montmartre has preserved its old village feeling.  Being on a hill, it couldn’t be destroyed by Haussmann’s straight architecture.

Interesting, as a side note, that Haussmann’s influence is still seen on the most mundane level, too.  At periodic intervals each day, water gushes from manmade artesian springs to wash the gutters of Paris’s streets and boulevards -- a Haussman innovation, some would say obsession for transforming the Paris of old to a clean city... organizing not only its civil defense and its traffic flow, but also the flow of its effluent, as well. 

Also interesting, as a side note, that the USA would invite a Parisian, Pierre l’Enfant, to transform the urban design of Washington, DC, on the same scale. 

Notwithstanding the extreme make-over, Paris edifices and monuments, pre- and post-Haussmann, are impressive and well preserved. You cannot miss the French Renaissance Louvre and its ultra-modern glass pyramid; the opulent Neo-Baroque (Napoleon III) Opéra de Paris built by Garnier in the second half of the 19th century (a good tour for those not having the time to visit Versailles); of course, the Eiffel Tower made out of iron for the Universal Exhibition of 1900; the High-tech Modern Centre Georges Pompidou with its appearing have been built "inside-out" with its external multicoloured infrastructure, built by Rogers and Piano in the 1970s.

Among monumental projects of President François Mitterrand, don’t miss the Grande Arche of the Défense (close western suburb of Paris) that stands right in the line of the Arc de Triomphe, the Champs-Elysées, the Tuileries' Carousel, and the Louvre’s pyramid; the French National Library (Bibliothèque François Mitterrand), located on the left bank of the Seine, near Bercy, with its L-shaped towers of books (symbolizing open books) arranged at the corners of a giant platform around a sunken garden.

Chapels, Churches, Cathedrals

Noted here under "Architecture" rather than "Religion", Paris's religious edifices captivate the religious and non-religious alike, and perhaps are among the reasons Paris is considered to be - like Rome, London, Florence, Madrid, Vienna, Moscow, Montreal and Venice - among the "great" cities of the world. They certainly represent vision of the highest order, and once were among the highest accomplishments of Western civilization. Today, they offer not only a feeling of awe or closeness with an ancient past that is rare …they can offer a cool, restful and contemplative respite in the heat of a summer trip. On a Saturday night or Sunday, their massive organs will literally move you. Also, in the spring, summer and autumn, organizations of classical musicians give very low-priced concerts ranging from ensembles performing Bach and Vivaldi concertos, to full choirs and orchestras doing Mozart's "Requiem". Usually the "cheap seats" are 10-15€, and it’s 20-25€ to sit in the front half of the church. Bulletins in the weekly tourist magazines and handbills announce these musical gems.

Cathédrale de Notre Dame de Paris - The "grand dame" (coining the term?). Perhaps the only place in this litany that’s beyond description. It must be seen, circled, entered and experienced. Probably the most famous in Middle Age French Gothic arts, rivaling any basilica, cathedral or minster in the world, in sheer mass and indoor as well as outdoor design. Among many major historical events, perhaps the most famous was Napoleon’s mischief here in 1804. Construction began 1163 on the site of the Cathedral of Saint-Etienne (528), and spread over centuries.

Basilique du Sacré-Cœur - Location, location, location - and a vision for the majesty and grace that Montmartre deserves - inspired the architects of what is perhaps THE architectural feature whose pure-white travertine can be seen from all over Paris - and from whence virtually all Paris can be inhaled. They were motivated by countless donations from all walks of life, and all over France, given in gratitude for Paris being spared in the Franco-Prussian War -- and in memory of those who gave their lives in it. (The government took over when they weren’t enough.) The exterior is as lofty, billowy and light as a cloud. The huge gold Byzantine mosaic inside the ceiling dome (apse) seems to move with the eye. Its tower amplifies a named bell, the 19-ton “Savoyarde”. Built 1875-1914 in the Romano-Byzantine style, but not consecrated until 1919, after The Great War ended.

La Sainte-Chapelle - French Court Gothic, with walls dominated by stain glass. On a sunny day, and some cloudy ones, the light through these windows will dazzle. Do not be disappointed if you enter at ground level. It's upstairs! When you feel as though you are inside a jeweled crown, you’re there. Steps from Notre Dame. Built 1246-48 under King Louis IX (Saint Louis).

La Madeleine (Sainte-Marie-Madeleine) - Inspired by the Pantheon, started in 1764, it was re-conceived by Napoleon as the temple to the glory of the «Grande Armée » in 1806. (Napoleon subsequently substituted the Arc de Triomphe in this role.) The edifice was determined by Louis XVIII in 1815 to become a church. After his death, it was “re-purposed” to become a rail station. In 1842, it became the church that it is today.

Saint-Sulpice - The largest and most ornate Jesuit-style church. Same spot occupied by churches since at least the 9th century. Currently more famous for its prominence in a controversial book and movie. Look for the sign: “Contrary to fanciful allegations in a recent novel, this is not a vestige of a pagan temple. No such temple ever existed in this place. It was never called a ‘rose-line‘. It does not coincide with the meridian traced through the middle of the Paris Observatory which serves as a reference for maps where longitudes are measured in degrees East or West of Paris. No mystical notion can be derived from this.” Since long before the book, the church was ALSO known for having the largest organ in Europe (now superseded by Notre Dame) …and, yes, for its meridian line, the “Astronomical Gneoman”, officially commissioned to determine the exact date of Easter, the equinoxes and the solstices. Since we know what it is not, what should you believe? Built 1646-1745.

Sainte-Eustache - This massive flying-buttressed and columned Gothic edifice near Châtelet-Les Halles is less-visited and less-restored than others in Paris. But it is no less impressive. Standing where its predecessor first appeared at the beginning of the 13th century, the current edition was built between 1532-1637. The structure is Gothic, but the decor is Renaissance -- its interior dark and cavernous.  Its grand organ has 8,000 pipes. Interred here: Molière, Richelieu, and the marquise de Pompadour. (In the place outside is Henri de Miller's huge modern head and hand sculpture, but that‘s another story.)

Basilique Saint-Denis - A few km from central Paris, it is the royal necropolis of France -- sort of. The current edition was begun in the 12th century, and completed in 1270. It is the first Carolingian church, and the first major Gothic church. Named for the martyred first bishop of Paris, the first abbey, supported by Charlemagne, was on this spot by the 7th century. During the revolution, the church was looted, and the royal remains were exhumed (a euphemism) and buried in a common grave. Napoleon, and then Louis XVIII, restored it. Today, the chancel of St. Denis is glorious. It houses the tombs of the French monarchy, from Medieval recumbent figures to spectacular Renaissance graves. But they are empty…

La Abbatiale Saint-Germain-des-Prés - Gothic and Romanesque, not among the larger of Paris, it may be the oldest. The original abbey existed in the 6th century, reportedly harboring St. Vincent‘s tunic, and thus was a destination for pilgrims. Destroyed by Normans in the 9th century, it was rebuilt in the 11th and 12th as a Benedictine abbey. As with all French churches, it was looted and burned during the revolution. Major restorations took place in the late 18th century, and in the 1990s. Today, the largest of three towers and the choir remain from before the revolution. And today, the church continues to anchor one of the most romantic, intellectual crossroads in Paris, a place and a neighborhood that many in France consider to be one of the cradles of very modern French civilization. Final resting place of René Descartes‘ heart (!) and several Merovingian kings. Also the venue of lovely evening concerts enhanced by the church’s excellent pre-microphone acoustics.

Cathédrale Saint-Louis-des-Invalides - Included in the complex are l’Église des Soldats (1676-1679) and l’Église du Dôme (1676-1706) . Initiated by Louis XIV in 1670, the beautiful golden-domed French Renaissance veterans’ hospital church dominates the vista when approached via the long lawn Esplanade des Invalides, that extends from the end of the ornate Pont Alexandre III on the Seine to the cathedral. The spire reaches 101m. It was re-gilded for the fifth time in 1989, using 550,000 gold leaves; e.g., more than 20 pounds of gold. Oh, yes -- here lies in priceless splendor Napoleon Bonaparte. His victories are inscribed around the tomb, including Moscow, which is not elsewhere on Napoleon's victory side of the ledger.

Saint-Augustin - An infant among the other ancients noted here, this church offers sanctuary from the din of the busy Bd. Malesherbes and Bd. Haussmann, where cars whisk by at dizzying speed -- and from the shopping at Paris‘s two most famous stores, just 200m near. Commissioned by Napoleon III, it was built from 1860 to 1871, the first with a steel superstructure. Its enormous, almost 100m high dome -- its main external feature -- is dizzying to look at from human-level inside. Another dominant interior characteristic is the prominent steel framing and other metalwork, emblematic of the industrial age. At human-level, there is much in this sanctuary that is by and celebrating the children of its congregation …a very warm greeting in a superstructure that otherwise might bring to mind the word “gaping”. (However, its large circular windows make it very light and airy throughout.)

L’église de la Sainte-Trinité - If you’ve come into town or departed for CDG airport in surface transportation, this is the one you've seen. It’s not that it’s large, just that it’s located at the confluence of important thoroughfares. It may be one of Paris’s best-kept secrets if you compare how many people have seen it, so many times, with how few have gone inside. Completed in 1867, in the heart of the Second Empire, it’s young by Paris standards, yet it doesn’t look young. Some say its exterior looks like a church on a church (…on a church etc.), and no surface - vertical or horizontal - goes idle. By contrast, the inside is tranquil, and much lighter than one might expect from the external coverage. Following recent cleaning, the exterior is light stone, and the bright light illuminates the bright colors that fill its interior.  A scene from Truffaut's Les Quatre Cent Coups was filmed here.

This website has a comprehensive listing of the Architecture of Paris.