The Olympic Games are a series of sport events occurring every two years, alternating between summer and winter sports.
In the early years, Summer Olympics were often held over a course of several months and competitors were not clearly separate from the general population, meaning pretty much anybody could show up and participate. Similarly, venues were rarely purpose built and permanent. Several of the pre World War I games were held together with a World Exhibition and several of the Olympic traditions actually date back to "Intercalated Games" that were to be held between two regular games and always in Athens but abandoned after one such event was held.
Since the 1988 Summer Games, all Olympic Games have been followed immediately by the Paralympic Games for disability sports in the same city and using most if not all of the same venues. Joint hosting of the Olympics and Paralympics (both Summer and Winter) has been official policy since 2001.
- Amsterdam – hosted in 1928; had previously hosted some sailing events at the 1920 Games.
- Antwerp – hosted in 1920.
- Athens - hosted the original 1896 Games and again in 2004, plus the only Intercalated Games in 1906; surprisingly little remains even from the 2004 Games.
- Atlanta - hosted in 1996. Most of the infrastructure still stands, but the main stadium was reconfigured for baseball immediately after the Games and is now being reconfigured again for American football.
- Barcelona – hosted in 1992. Most of the Olympic infrastructure still stands.
- Beijing – hosted in 2008, and will become the first city to have hosted both the Summer and Winter Games in 2022.
- Berlin - planned host for the 1916 games; ultimately hosted the 1936 games awarded before Hitler took over. Olympiastadion redesigned but still extant. Some other venues still extant in some form but hard to see for the casual observer.
- Helsinki – scheduled to host the games in 1940 (after Tokyo gave them back to the IOC due to the Pacific War); due to World War II, they were postponed until 1952. The Olympic stadium has been the most important outdoor sports venue in Helsinki ever since, but is currently closed for a major renovation which will last until 2019.
- London – the first city to host three Olympics (1908, 1948, 2012), with most of the 2012 infrastructure still present.
- Los Angeles – hosted 1932 and 1984 Olympics, the latter with a large Soviet-led boycott, and will host in 2028. The main stadium in both 1932 and 1984, the Los Angeles Memorial Coliseum, is still in active use and is planned to be used in 2028 as well. Some of the other 1932 infrastructure and much more of the 1984 infrastructure still stands.
- Melbourne – hosted in 1956 with the exception of equestrian events, which were held in Stockholm due to Australian quarantine laws. The main stadium, the Melbourne Cricket Ground, is still in active use; it is mostly outwardly unchanged from its Olympic configuration, although significantly modernised within.
- Mexico City - hosted the 1968 games where many records were broken due to high altitude, but several political controversies overshadowed the events.
- Montreal - famously bankrupted itself with the 1976 games that cost more than expected, especially the Olympic Stadium that proved a less than inspired design and would struggle for years to find a suitable tenant.
- Moscow - hosted in 1980 with a large US-led boycott. The main stadium is currently being renovated for the 2018 FIFA World Cup.
- Munich - host of the 1972 Olympics, which was overshadowed by a terrorist attack that led to the deaths of 11 Israeli team members. Much of the Olympic infrastructure (including Olympiastadion) is still present. The U-Bahn (Germany's third) opened a year ahead of the game and was partly built for the games
- Paris – hosted 1900 and 1924 Olympics, and will host in 2024. The main stadium from 1924, located in the suburb of Colombes, still stands and will be used for field hockey in 2024, but has been heavily downsized from its 1924 configuration.
- Rio de Janeiro - hosted in 2016 after Brazil had already hosted the 2014 FIFA World Cup; many venues are already beyond use or were never planned to be permanent.
- Rome - hosted in 1960; the first city of one of the major Axis Powers of WWII to host after the war. The main stadium is still in use, though it was extensively renovated for the 1990 FIFA World Cup.
- Seoul - hosted in 1988 after an attempt to jointly host with sites in North Korea fell through. Most of the Olympic infrastructure still stands.
- St. Louis - hosted in 1904. The main stadium, located just outside the city limits, still exists on the campus of Washington University, but has been heavily renovated.
- Stockholm – hosted in 1912, and also hosted equestrian events in 1956.
- Sydney - hosted in 2000. Most of the Olympic infrastructure still stands.
- Tokyo – the next Summer Olympics host in 2020; also hosted in 1964, with the first Shinkansen running just in time for the 1964 Games.
Originally Winter Olympics were held in the same year as Summer Olympics and often in the same country. With the increasing size of the Olympic Games and the increasing financial commitment for hosts, it was decided to split Summer and Winter Games up and Winter Olympics were scheduled to be in the year of the Soccer World Cup to avoid the two biggest worldwide sports events going head to head.
Similarly to the Summer Games, each Winter Olympics since 1992 has been immediately followed by the Winter Paralympics, also in the same host city and using the same venues.
- Albertville – hosted in 1992. Most of the infrastructure still stands, though some of it has been renovated. The stadium used for the opening and closing ceremonies was intended to be temporary and was removed immediately after the Olympics, with parts of it used in that year's Summer Games in Barcelona. A monument stands on the site today.
- Calgary – hosted in 1988, with almost all of the Olympic infrastructure (much of which is in surrounding areas) still present.
- Chamonix - hosted the very first Winter Olympics in 1924.
- Cortina d'Ampezzo – hosted in 1956, after having been named as the host of the 1944 Games that had been scrapped due to World War II.
- Garmisch-Partenkirchen – hosted in 1936; less overtly Nazified than that year's Summer Games in Berlin.
- Grenoble – hosted in 1968.
- Innsbruck – hosted in 1964 and 1976, the latter time on short notice after voters in Denver turned down hosting duties.
- Lake Placid – hosted in 1932 and 1980. The 1980 Games used much of the 1932 infrastructure. Most of the venues still exist; the most notable exception is that the 1980 luge track was demolished and replaced with a new track for all sliding sports (bobsled, luge, skeleton). The site of the 1980 "Miracle on Ice", in which the US men's hockey team defeated the heavily favored Soviets, has since been renamed after the 1980 team's head coach Herb Brooks.
- Lillehammer – hosted in 1994.
- Nagano – hosted in 1998.
- Oslo – hosted in 1952.
- Pyeongchang – the next host in 2018.
- Salt Lake City – hosted in 2002, with almost all of the Olympic infrastructure (much of which is in outlying areas) still present. The area's current light rail system was started as transportation for the Games.
- Sapporo – hosted the first Winter Games in Asia in 1972. Had been named as the 1940 host, but WWII scuttled that plan.
- Sarajevo – hosted in 1984. Most of the infrastructure was damaged or destroyed during the Bosnian War of the 1990s. The city's main indoor arena was built on the foundation of the 1984 indoor arena that had been destroyed in the war.
- Sochi - hosted in 2014; the most expensive Winter Games to date.
- Squaw Valley – hosted in 1960.
- St. Moritz – hosted in 1928 and 1948.
- Turin – hosted in 2006.
- Vancouver – hosted in 2010. Almost all of the infrastructure, both in Vancouver and in the Whistler resort area, still stands. However, the main stadium, BC Place, which had an air-supported roof in 2010, now has a cable-supported retractable roof.
Accessibility of tickets varies greatly. Opening and closing ceremonies, as well as finals, are very desired, while tickets to minor events can in some cases be obtained at entrance. The ability to acquire tickets also depends on the host. While tickets for Handball events were easy to get in Rio, they'll likely be much more in demand in Paris.
Availability of travel accommodation has varied a lot between games. As a general rule: The smaller the city, the bigger the price-gouging.