Vienna
A last-minute change of itinerary had us looking for a European city to go, Vienna 'popped' up. In recent years, it has been ranked as the most livable city in the world, and is about two hours from London by flight. The airfare was reasonable but by then, the hotel prices in the city had gotten very expensive (... hotel further away from the city centre should solve this "monetary obstacle"). 
Arrival
The hotel was about 20 minutes by tram from the city centre. The hotel staff was slightly bemused when we asked what places of interest there were to visit, rather than asking for directions to said places of interests. Anyway, he recommended taking the subway to St. Stephan's Cathedral.
We caught sight of St. Stephans Cathedral the moment we emerged from the subway escalator. It was striking and imposing against the blue sky and it "flushed" away our jet lag and any glumness :).
Walking
In between visits to the museums and Christmas Markets, we spent our time walking about the old historic centre, which is a UNESCO World Heritage Centre. The streets are always bustling with locals and tourists, and Christmas decorations made for a very festive atmosphere.
Most turns around corners and blocks led to interesting architectural sites and elaborate art displays. It grew slightly tedious to read up on one particular sculpture, just as another magnificent building came along, with another striking statue within view.
After the initial period of stopping to do "fact-finding" on the many interesting buildings around us, we proceed to walk, relax, immerse in the sights and sounds, and simply read the available displayed plaque to any other prominent landmarks we saw around us.
The shopping streets crowded with shoppers and tourists.
St.Peter Church
St. Peter Church is a beautiful church that was hosting a (free, open to public) organ performance. It was a good place to rest our tired feets, while we took in the soothing music. There was a certain grandness to the place; the murals and sculptures lining the place were intricately and elaborately designed, with many gold features.
Free Morning Walking Tour
We booked a free morning tour, and met with the tour guide at the Jewish memorial beside the Albertina Museum.
The three hours of walking through the historic centre was very informative. The guide said that it is very difficult to qualify as a licensed tour-guide because one needed to have in-depth knowledge of Vienna's history and its landmarks to pass the test.
She was certainly very knowledgeable, and as she spoke we realised there was so much about the Austria and Vienna's history that we didn't know about!
We got two interesting tips from the guide:- a different performance is hosted daily at the State Opera where a 3-euro standing ticket would be available for purchase and secondly, the climb up to St.stephan cathedral tower was the best way to get a panoramic view of Vienna.
St. Stephans South Tower
We planned our climb for after lunch. We had anticipated that it would be a tough climb.
What we hadn't anticipated was how narrow the spiral stairs would be; there was room enough only for one person at a time. Nevertheless, we got glimpses of the view outside as we ascended, which already gave us a nice view of the city.
Although the weather was cold, the sun shone splendidly on the city that stretched far into the skyline.
Vienna State Opera
The construction of the building was completed in 1869, and the premiere performance was Don Giovanni by Mozart. It is one of the busiest opera houses in the world producing many operas in a repertory system per year.
There was a short queue for the three-euros "Standing room only" tickets. We were thrilled when we managed to snag tickets, despite it being a performance we knew nothing about. To us, being able to step into the theatre as a spectator was, in itself, worth the three-euros.
Since we arrived late, the middle standing room area was already full, and we were directed to the side of the standing area. Alas, we only had half the view of the stage of a modern-day ballet performance of Peer Gynt. Still we stayed till the first interval.
We queued again in the State Opera on the second evening. The queue was much longer because the show was M.Butterfly. The tickets sold out before our turn... What should we do with the evening?
We made our way to St. Peter's church for a short evening organ performance.
Naschmarkt
We left the hotel early for a visit to the Naschmarkt before our morning tour. Only some of the shops were open early for business.
We had wanted to have a Chinese breakfast since there was a supposed to have a higher concentration of Chinese shops in the area. However, the shops alongside Naschmarkt were still closed.
We walked through the long alley between the shops. I imagined it would be lively and crowded when all the shops were open.
Food
Some of the must-try foods in Vienna are Wiener Schnitzel, Apelstudel, Sachertorte and definitely a few cups of coffee.
Cafe Central
We passed by Cafe Central a few times and the queue was always exceedingly long. On a rare occasion when it wasn't, we decided to join the (short) queue for the opportunity to have Scahertorte and a cup of cappuccino in this well known cafe during a rainy afternoon.
We had our first Schnitzel and Apfelstrudel during our first meal in Vienna at the Albertina museum.
Since the Chinese cafe was closed for breakfast, we had our breakfast in a beautifully decorated cafe along Naschmarkt.
We wanted some Asian food :- Japanese lunch and a Chinese tea break of dumplings (eaten without photo op) and chili-chicken.
We also had a nice dinner at a restaurant to try another Wiener Schnitzel.
There are many restaurants and cafes serving Local and European cuisine, and a proliferation of fast-food outlets in the subway stations and along the streets. We balanced our food budget by eating at some of these cheaper cafes and fast-food joints.
Along the way, we learnt that we were not supposed to request for the server's attention when ordering food. Also, when they come to the table with the bill, we have to inform the server how much we wanted to leave as a tip (several possible tip percentages are printed on the bill).
Thought:
Originally, we had wanted to travel to the Isle of Skye at Scotland from London, and then to proceed to Greece. However, it did not seen the most ideal time for Isle of Skye (what if we encountered a storm, and got delayed and were unable to go Greece?!). Vienna was indeed a good alternative.
Many conducted tours included Vienna as a one or two days visit as part of a greater Europe trip (as was my trip many many years ago), it was good that we had 5 days to explore Vienna for this trip.
Vienna Historic Centre is an excellent UNESCO World heritage Site, and it is a very livable city on every count. Still, my hometown"village" is my most livable city. :)
On the Same Trip
Vienna Schönbrunn Palace and Belvedere Museum
Museums : Albertina, Imperial Treasury and State Hall of Austrian National Library
Austria Vienna Christmas Markets - Night and Day
Other Information:
Hotel : ibis Hotel Wien Hauptbahnhof
Transport : Comprehensive tram and subway systems
Wikipedia : Vienna