Few countries could surpass Lithuania in size and lavishness of its churches if you take local population numbers into account. Furthermore, Lithuanian art of making elaborate crosses is inscribed in the UNESCO list of immaterial world heritage.
Nowhere this is felt more than in the Hill of Crosses (a unique-in-the-world site where millions of pilgrims have erected hundreds of thousands of crosses over more than a century). Arguably it is the most famous sight in Lithuania. A symbol of religion, anti-Soviet resistance and a powerful work of art all at once the Hill of Crosses impresses Christians and non-Christians alike.
Religiously however the center of Catholic life in Lithuania is in Šiluva. In this Samogitian village the Europe's first church-recognised apparition of Virgin Mary took place in 1608. The yearly celebrations (September 8th-16th) attract many thousands.
Almost every Lithuanian town and larger village have a Catholic church that feels far too massive for the settlement's population. This is because Catholicism always dominated the religious landscape (80%+ follows it) and there was no serious religious fragmentation for centuries. The older town and village churches (pre-1860) are typically smaller and wooden while the early 20th-century revivalist ones easily dwarf their surroundings in size. There is even a separate Lithuanian word meaning "Village with a Catholic church" (bažnytkaimis).
The most impressive collection of churches is in Vilnius Old Town where there are almost 30 such pearls of Gothic and Baroque. Most famous are St. Anne (for its exterior), Divine Mercy and the Gate of Dawn (both for miraculous paintings with worldwide following). Other boroughs of Vilnius also have a fair share of imposing churches (St. Peter and Paul being the most famous). So does the city of Kaunas.
In cities and towns one may also find Russian Orthodox churches. The largest and most important ones are once again in Vilnius where Holy Spirit church includes bodies of three Orthodox saints. Old Believer, Lutheran, Reformed Christian, Eastern Rite Catholic, Jewish, Muslim and Karaite religious buildings also exist, many of them predating the 20th century.
There is a long tradition in Lithuania of erecting crosses, chapels and chapel-posts (miniature chapels) at roadsides, cemeteries and courtyards. Countless of them were destroyed by the Soviet occupational power but many still remain. Some locations known as the holy places (šventvietė) became minor replicas of the Hill of Crosses.