City sprawl into the hills as seen from The Top high-level bar. Oslo's iconic Olympic ski jump is barely visible in the distance. 
You know it's coming, the long daylight hours, but it still takes you by surprise, and you find it weird for a long time. Sunrise is at 04 in the morning, and sunset is not until 10 at night! What with twilight etc full darkness hardly occurs at all. It is just daylight all the time, and it takes some getting used to. No wonder hotel reviewers on the web talk about blackout curtains as well as the perennial favourite, the quality of breakfast!
Oslo is replete with statues, fountains and outdoor cafes, this one in the colonnade surrounding the city Cathedral. 
The airport is a long way out of town, so we saved big money on a taxi by catching the FlyToGet highspeed train which runs from inside the arrivals hall into the city in 19 minutes every 10 minutes. That is a great service, in a fast clean train which actually had room for all our luggage. Our hotel was within walking distance (and not a single step!) of the large modern station which is Oslo S, and very kind railway staff helped us with directions.
The Akerselva river runs from the hills of Oslo, past our hotel, and into the waters of the fjord. 
The very top of our hotel contained the gym. It was a workout just to get there, requiring a five storey climb! 
We totally forgot that Norway is not a member of the European Union (having voted "no" in two referenda) and our EUR currency was useless there. But so far we have found that plastic is universally accepted and did not had any need for Norwegian krones (except for one merchant whose terminal had broken). However you look at it, with the exchange rate, everything is very expensive for us (Australians) here, maybe about twice or more the prices we would pay at home.
The European love of al fresco dining is alive and well in Oslo. Here, along sunny Karl Johans gate on a warm evening. 
Oslo is officially a global city despite it's modest size, with an urban population of about 1.5M. We found it to be a fascinating blend of the old and the new, the old reflected in magnificent historical buildings, including military forts parts of which date back 500 years, and wonderful civic buildings several centuries younger, and the new with a magnificent public transport system (we managed to use trains, trams and buses to get around) and ultra-modern building projects in and around a part of town whose name Bjorvikameans "city bay". Here there be intensive apartment developments, but also the splendid Norwegian National Opera and Ballet as well as the (Edvard) Munch Museum / Art Gallery, home of The Scream.
New high-density apartment construction in Bjorvika, Oslo makes good use of the fjord water over which they are built. 
To us as visitors, it seems like Oslo is a cool, calm and collected city. Everyone seems to be relaxed, and moves around in a sense of relaxation and happiness. Part of this overall feeling must be the traffic, or lack of it. Somehow, Oslo has found a way to keep traffic out of the inner city. There must be restrictions, a congestion toll or something. There are taxis and delivery trucks, trams and buses, but very few private cars. What a delight that makes it for pedestrians!
Oslo lies at the northern end of the 50km long Oslofjord, one of 1700 named fjords in the country, and indeed the name fjord is derived from ancient Norwegian. So deep into a fjord offers extraordinary protection, so it is little wonder that fjords make good ports, and, in Oslo, we saw nothing but calm waters and numerous facilities designed for locals to take advantage of them, like artificial beaches, kayaking ramps, marked lap swimming zones, sauna cool-offs. The water is 10-11C in May and so we were not tempted to dive in. That said, the locals take it in their stride, and we saw many people jumping in, having jogged or ridden to the edge, or freshly heated up in one of the numerous public waterside saunas.
A large aquatic recreation area in Bjorvika, Oslo was popular with casual swimmers but only a few ducks were taking advantage of the marked lap lanes. 
We were entertained by an orchestra's free concert in this gazebo in a park near the National Theatre, while we imbibed in an adjacent open-air cafe. 
A bold statue of King Christian IV (1577-1648) overlooks the square in front of the grand Glasmagasinet department store. He was a popular reformer who ruled Denmark and Norway. 
Norway is a consitutional monarchy with King Harald V having reigned since 1991. The grounds of the Royal Palace lie at the opposite end of Karl Johans Gate to the Oslo S railway station, and they are effectively a public park, and a popular one at that, with many people walking and relaxing there in the sunshine during our visit. During the world wars, Norway was a neutral country but this served them no good when it was forcibly occupied by Nazi Germany for 5 years. The efforts and bravery of the resultant resistance movement is memorialised in a museum in the huge grounds of the medieval Akershus Fortress quite near downtown. Construction here started in 1290AD. Wikipedia says that it "has successfully survived all sieges, primarily by Swedish forces, including those by forces led by Charles XII in 1716" although it did surrender to the Nazis in 1940.
Unlike at least one other monarchy, the approach to the Royal Palace is in a public park and free of any restrictions until you get really close. 
A guard on duty at the Royal Palace setting off to raise the bollards preventing vehicular but not pedestrian access to the grounds. 
Seemingly aimed at the Aida, a cruise ship visiting Oslo, a canon guards the boundary of Akershus Fortress. 
The National Monument for the Victims of (the second World) War, in the grounds of Akershus Fortress. 
Overlooking the city is a sculpture garden in a large park called Ekebergparken. We caught the tram up to the park and walked back into town afterwards. The garden has 45 impressive artworks scattered over a large area of forest of great diversity. We notice the curators (both here and in town) have a particular interest in the nude form as well as very modern approaches to artistic creation. One in particular was quite ephemeral, being a water misting system which operated intermittently to create a dense fog which rolled around the forested slope and valley nearby. Our visit here was most enjoyable, although we were put off by the price charged for a simple map, and to use the toilet.
Chloe (2019) by Jaume Plensa in Ekebergparken sculpture garden is like an optical illusion from any angle. 
This is artwork in the Ekebergparken, Pathfinder Oslo (2016) by Fujiko Nakaya, is a misty fog lasting 15 minutes several times a day. 
One day we visited the botanic garden near the suburb of Toyen. This unheralded place was very popular with locals, elderly people (us included) and families. One of the temperate houses was named after Queen Victoria, and one contained a rather sad and dusty specimen of the Australian Wollemi Pine. Maybe it was just too dry in that environment to be happy?.