The Northeasternmost area of Poland is unique in the world. This is the only area beyond the Lithuanian boundaries where Lithuanians make the majority (~80%). Lituanity is felt here even better than in Lithuania itself: home fences and even a derelict former gas station bear patriotic symbols such as the towers of Gediminas. Many signs are bilingual Polish and Lithuanian. Unlike in Lithuania, in Poland bilingual signs are permitted in minority-majority areas. There has been situations however when vandals damaged the Lithuanian part of the signs but ~2013 most have been rebuilt.
The capital of Poland's Lithuania is Punsk (Punskas, pop. 1200). Its Accension church yard hosts a monument to Lithuanian anti-Soviet partisans. The daily mass is celebrated in Lithuanian and only in Sundays there is a single Polish mass. Church interior is more Polish however, with gold-plaqued statues of saints. Lithuanian museum is nearby. There are two of them in Punsk: Juozas Vaina ethnographic museum and Punsk history museum.
The greatest modern gem of Punskas area is the Prussian-Yotvingian settlement in Ožkiniai village (2 km south of Punsk). Prussians and Yotvingians were Baltic tribes (related to Lithuanians) annihilated by German crusaders; they remained pagan and left few historical descriptions. Nonetheless a local Lithuanian businessman enthusiastically builds up the massive locality since 2001. No one can tell if it looks authentic or not but it certainly feels atmospheric and believavle, with a small castle surounded by a ditch, a village, places for sacred fires, Baltic heroes path of fame. The settlement is well integrated with the local forest and no modern edifices are visible from no locations. One can feel as in the past; both Poles and Lithuanians bring their excursions here and Baltic neo-pagans celebrate their holidays.
A more traditional open-air museum (skansen) is located going from Punsk towards Sejny. It includes a 19th century 5-building farmstead full of museum materials, there is a barn and an inn and all these are outflanked by a modest Žalgiris battle monument. Recent extensions include two "tents of masters" (one for a language master and another one for music master) and improvised ground labyrinth that leads to a written folktale of "Eglė the Queen of Serpents" (in Lithuanian, Polish and Belarusian), an observation point, and some activities. An annual amateur village theater festival takes place here.
Minor places of interest around Punsk are a stone commemorating 1990 Lithuanian independence restoration (in Kampuočiai), a memorial for knygnešys P. Matulevičius (1956, in Kreivėnai), Vytautas the Great memorial (1930, Burbiškiai). There are many stone crosses with Lithuanian inscriptions.
The largest town in area is Sejny (Seinai, pop. 6000). It is an old diocesan centre, anchored on the 1632 Virgin Mary church. The castle-like former priest seminary and monastery stands nearby. Sejny was once a Lithuanian town and the early 19th century creators of the seminary claimed that people in Sejny area "speaks little Polish". During the Lithuanian National Revival Sejny has been an important center of Lituanity where a Lithuanian "Šaltinis" newspaper used to published since 1906. At 1897 a Lithuanian writer Antanas Baranauskas became Sejny bishop (his sculpture has been constructed in 1999 in front of the church under Lithuanian efforts; he is buried under the church). Author of the Lithuanian National Anthem Vincas Kudirka as well as Vincas Mykolaitis-Putinas who later wrote a semi-autobiographical book on priest's celibacy/love dilemma, both studied at the seminary. Out of the 25 students in 1829 21 were ethnic Lithuanians.
The final fate of Seinai (and Punskas) has been decided in years 1919-1920. Both Lithuania and Poland were newly independent and were partitioning the lands of the former Commonwealth. The power in Seinai/Sejny switched many times these years, but the 1920 capture of the town by Polish forces proved to be final (the Poles continued their advance on Vilnius and Eastern Lithuania, and the bitter Polish-Lithuanian territorial dispute continued until World War 2). Berzniki village cemetary is full of the reminiscences of those days. Lithuania has recently built a gravestone with the inscription "To those died for motherland freedom" there for its fallen soldiers of the 1920 battle. Some Poles protested the inscription claiming that these soldiers died when attacking Poland. One opponent was a local priest who initiated construction of a neighboring "Ponary cross" for "Polish civilians killed by Lithuanians in World War 2" (even though the Berzniki cemetary has no graves of such victims). On the other side of the Lithuanian memorial a stone with a list of Polish-conquered cities in 1920 now stands (among them the Lithuanian town of Druskininkai). Furthermore an "alternative" memorial for Lithuanian soldiers was built by the Polish side - a cross beyond the cemetery wall where an inscription declares that Lithuanians helped the Russians to attack Poland. All these events created a diplomatic friction and even caused Poland's Lithuanians to appeal to a Vatican nuncio claiming the priest's actions are against Christian spirit.
The true events of the era were such: "Lithuanian" and "Pole" were a political choice rather than just ethnic categories: many people of Eastern Lithuania spoke Polish better than Lithuanian even though they were of Lithuanian origins (due to a centuries-long linguistic shift). Lithuania considered them to be Lithuanians, Poland considered them Poles (and sometimes even held the entire Lithuanian nation to be a subset of Polish nation). A war started and its results still cause some Poles and Lithuanians to dislike the other nation. This hate came through during the World War 2 when there were both Poles who murdered Lithuanian civilians and Lithuanians who murdered Polish civilians (the Berzniki cross however remembers only the latter). The Polish-Lithuanian war partly overlapped with the Polish-Russian war, that's why Lithuanians are accused of helping Russians (even though Lithuanians and Russians had a different agenda and even fought each other in the same volatile 1918-1922 period).
Currently Sejny is ~17% Lithuanian and there are few Lithuanian inscriptions but the town is still a center of Lithuanian culture. Lithuanian mass is celebrated in the church, a Lithuanian consulate is nearby, there is a Lithuanian "Žiburys" school (2005), cultural center "Lithuanian home" (1999), bi-weekly newspaper "Aušra".
Punsk and Sejny area forms just a small part of Podlaskie (Lithuanian: Palenkė) Voivodship. This territory of 1 200 000 inhabittants with a captal in Bialystok (Lithuanian: Balstogė) was part of the Lithuanian Grand Duchy until the Polish-Lithuanian Union of Lublin (1569). The name "Palenkė" means "[A Lithuanian land] next to Poland". The modern voivodship has been established in 1999 but its coat of arms reminds its history: it is a combination of the Polish eagle and Lithuanian vytis. Vytis is also used in the coats of arms of Bialystok, Bransk, Sedica and other cities/towns; many cities/towns of the area has historical Lithuanian names that are not a simple transliteration of the Polish ones.