According to forum posts, some travelers recommend exploring nearby islands in the Oslo fjord, like Oscarsborg, or taking day trips to places such as Lillehammer, Fredrikstad, or Drammen. Options for architecture enthusiasts include visiting the Blindern campus library or exploring the Frogner neighborhood to see brick buildings from the 1850s to 1900, inspired by Berlin.

Travelers have called out several cultural and historical sites worth visiting in Oslo. The Vigeland sculpture park and the Mausoleum of Emanuel Vigeland are popular for those interested in art and architecture. For history enthusiasts, the Akershus Fortress and the Royal Palace provide insights into Norway's past.

For unique local experiences, forum users suggest visiting the Mathallen Oslo food market or spending time in the Grünerløkka area, known for its vibrant atmosphere, local restaurants, and contemporary urban vibe.

According to forum posts, travelers recommend the Thon Hotel Opera for its proximity to Oslo Central Station, making it convenient for transportation and sightseeing. Another option mentioned is the Radisson Plaza, noted for views of the city or Oslofjord from upper floors, although it might not always be considered moderately priced.

Some travelers said that the Clarion Collection Hotel Folketeateret offers both breakfast and dinner, which can be a cost-effective option in an expensive city. Additionally, the First Hotel Millennium is praised for its location near key attractions like the Opera House and the Viking Digital Museum, offering a practical choice for families and sightseers.

For those seeking alternative accommodations, travelers have called out aparthotels like the Erik Vokel hotels in other cities, indicating a preference for accommodations that combine apartment-style living with hotel amenities. While specific names in Oslo weren't mentioned, users typically find similar accommodations through apartment booking platforms.

According to forum posts, Oslo offers a robust public transport system that includes buses, trams, metros, and ferries. Travelers can purchase 24-hour tickets that are valid across all these modes of transport.

Some travelers mentioned that tickets are available for multiple days, and these can be used for unlimited trips within selected zones. The Ruter app is frequently recommended for the ease of purchasing and managing tickets digitally.

For transportation from the airport to the city center, users can take the Flybussen, local trains, or the Flytoget express. The local train is noted as the cheapest and quickest option to the central station, with a short walk to the Oslo bus terminal.

Travelers have called out that downtown Oslo is quite compact and walkable, particularly around the Karl Johan Street area. For destinations like the Vigeland Sculpture Park, public transport is necessary, with trams or metros being convenient options.

According to forum posts, travelers have called out Oslo's rich options for outdoor enthusiasts. For those interested in skiing, Oslo provides access to a vast network of ski trails easily accessible by metro. Additionally, the Marka Forest offers a natural escape with extensive hiking trails and beautiful vistas.

Some travelers suggested spending time exploring Oslo's urban environment. This includes strolling through the city center, where historic and architectural landmarks like the Opera House and the Royal Palace are located. The Vigeland Sculpture Park and the waterfront area at Aker Brygge are also highlighted for leisurely walks.

For a cultural dive, forum posts recommend visiting the Oslo City Hall to view impressive murals and the Munch Museum for art enthusiasts. The city's diverse neighborhoods such as Grünerløkka are noted for their vibrant food scene and local shops, offering a contemporary urban stroll.

According to forum posts, Oslo is surrounded by expansive forests ideal for hiking, such as Marka, which includes Nordmarka and Østmarka. These forests feature numerous lakes, trails, and scenic viewpoints, accessible by public transport.

Some travelers mentioned the Oslofjord as a notable natural attraction, with options to visit nearby islands like Hovedøya via local ferries using regular transit tickets. These islands offer a mix of natural landscapes and historical sites, such as ancient monastery ruins.

For those interested in more distant natural scenery, areas like Lillehammer and Norefjell, which are about a 2-hour drive from Oslo, offer mountainous landscapes and are recommended for their beauty and outdoor activities.

According to forum posts, Oslo airport offers luggage storage services, with a link directed to the airport's official website for more details on these services.

Travelers have indicated that overnight stays at Oslo airport are feasible but may not be comfortable, citing limited facilities such as toilets and reclining chairs. An update from a traveler mentioned finding a suitable spot at a Burger King on the second floor, which had a few sofas suitable for sleeping.

Some travelers mentioned that Oslo airport houses duty-free shops located at both international arrivals and departures. Additionally, there are dining options available, including a Burger King that is open overnight and a 24-hour convenience store type outlet.

Forum posts highlighted that Oslo airport is equipped with elevators for easy access to different levels, including the train platform in the basement, making it convenient for travelers with mobility issues or those carrying luggage.

According to forum posts, Oslo predominantly accepts card payments, with nearly all transactions being done via this method. It's noted that even small vendors at markets tend to use portable card readers or mobile payment apps like Vipps.

Some travelers mentioned that it's still possible to use cash, particularly at supermarkets with manned checkouts and for certain public transport options, although it might involve additional costs. However, using cash is becoming increasingly difficult as it's less commonly accepted.

Travelers have pointed out that Visa and Mastercard are widely accepted, and it's advisable to choose the local currency (NOK) for transactions to get the best exchange rate. Prepaid cards like Revolut also work well, offering easy tracking and management of expenses.

According to forum posts, if travelers have a single through ticket involving a layover at OSL Airport, it is the airline's responsibility to ensure connections are feasible. Airlines typically do not sell tickets with impossible connections, implying that layover times are calculated based on minimum required intervals to catch connecting flights.

For travelers with separate tickets for connecting flights, the risk is higher. Some travelers mentioned that separate reservations do not provide the insurance of meeting connection times, unlike through tickets. The advice is to allow a minimum of 2-3 hours for layovers when booking separate tickets to accommodate any unforeseen delays, especially during winter when weather disruptions are likely.

Travelers have called out that automated transfer options, like direct routes to security checks, are generally not available if switching airlines or ticket types at OSL. This necessitates more time for customs, baggage claims, and check-ins, which must be considered when determining layover times.