Polish złoty in the context of The Deluge (Polish history)

The Deluge was a series of mid-17th-century military campaigns in the Polish–Lithuanian Commonwealth. In a stricter sense, the term refers to the Swedish invasion and occupation of the Commonwealth as a theatre of the Second Northern War (1655–1660) only; in Poland and Lithuania this period is called the Swedish Deluge (Polish: potop szwedzki, Lithuanian: švedų tvanas, Swedish: svenska syndafloden), or less commonly the Russo–Swedish Deluge (Polish: Potop szwedzko-rosyjski) due to the simultaneous Russo-Polish War. In a wider sense, it applies to the period between the Khmelnytsky Uprising of 1648 and the Truce of Andrusovo in 1667, comprising the Polish theatres of the Russo-Polish and Second Northern Wars. The term "deluge" (potop in Polish) was popularized by Henryk Sienkiewicz in his novel The Deluge (1886).

During the wars the Commonwealth lost approximately one third of its population as well as its status as a great power due to invasions by Sweden and Russia. According to Professor Andrzej Rottermund, manager of the Royal Castle in Warsaw, the destruction of Poland in the Deluge was more extensive than the destruction of the country in World War II. Rottermund claims that Swedish invaders robbed the Commonwealth of its most important riches, and most of the stolen items never returned to Poland. Warsaw, the capital of the Polish–Lithuanian Commonwealth, was destroyed by the Swedes, and out of a pre-war population of 20,000, only 2,000 remained in the city after the war. According to the 2012 Polish estimates, the material damage caused by the Swedish army amounted to 4 billion złotys. 188 cities and towns, 186 villages, 136 churches, 89 palaces, and 81 castles were completely destroyed in Poland.

A traveller's cheque is a medium of exchange that can be used in place of the currency of a country. Each cheque is denominated in a preprinted fixed, round, amount of one of a number of major world currencies; it has two panels for a signature. The purchaser signs one panel of each cheque on receiving it; to use it, it is signed on the second panel and dated in the presence of the payee, who accepts it if the signatures match. It can then be deposited into a bank account in the same way as a normal cheque; payment was guaranteed if the signatures matched, even if a cheque had been used fraudulently, for example stolen, encouraging merchants to accept them routinely. While it was possible for the issuer to go out of business, invalidating cheques, most issuers were large, stable, businesses.

Traveller's cheques were widely used from the 1850s to the 1990s by people travelling in foreign countries instead of cash, mainly before the introduction of payment cards and later electronic methods of payment. They were much safer for the traveller as their value would be reimbursed if stolen, unlike cash. A book of cheques of different amounts would be carried, to be cashed or spent as required. They could be exchanged for local currency at a bank, and many merchants accepted them as payment.

The Narodowy Bank Polski (pronounced [narɔdɔvɨ bank pɔlski]; the National Bank of Poland), often abbreviated to NBP, is the central bank of Poland, founded in 1945. It controls the issuing of Poland's currency, the Polish złoty. The bank is headquartered in Warsaw, and has branches in 16 major Polish cities. The NBP represents Poland in the European System of Central Banks, an EU organization. The bank doesn't translate its name to English but uses its Polish name Narodowy Bank Polski in all its English communications.

The NBP is also a member of the European Systemic Risk Board (ESRB).

POLIN Museum of the History of Polish Jews (Polish: Muzeum Historii Żydów Polskich) is a museum dedicated to preserving and recalling the memory of the history of Jews in Poland. The museum is located on the site of the former Warsaw Ghetto. The Hebrew word Polin in the museum's English name means either "Poland" or "rest here" and relates to a legend about the arrival of the first Jews to Poland. Construction of the museum in designated land in Muranów, Warsaw's prewar Jewish quarter, began in 2009, following an international architectural competition won by Finnish architects Rainer Mahlamäki and Ilmari Lahdelma.

Completed at a cost of 320 million zł, the museum opened on 19 April 2013 with the core exhibition, showcasing the thousand-year history of Polish Jews, opening on 28 October 2014. The museum's architecture features a minimalist exterior with glass fins and copper mesh, and an interior designed by Event Communications. A central feature is the cavernous entrance hall, symbolizing the fractured history of Polish Jews. The organizational structure of POLIN includes an academic team led by Barbara Kirshenblatt-Gimblett and chief historian Antony Polonsky.