I haven't received any Lithuanian cards through Postcrossing yet, but I have some from my penpals and I think it's time to share some old (well, not so old - I've received all of them during the last 4 years) cards with you :) I haven't been to Lithuania, but I've heard a lot about Vilnius, because Polish people have quite sentimental attitude to this city (it's the same as with Ukrainian city Lviv).
You can see Old Vilnius, Cathedral Bell Tower, Towers of the churches, paupio street and Pasazo street on this card. The Vilnius Old Town is also a UNESCO WHS.
Vilnius Old Town, the historical centre of Vilnius, is one of the largest in Europe (3.6 km²). The most valuable historic and cultural sites are concentrated here. The buildings in the old town — there are nearly 1,500 — were built over several centuries, creating a blend of many different architectural styles. Although Vilnius is known as a Baroque city, there are examples of Gothic (e.g. St Anne's Church), Renaissance, and other styles. The main sights of the city are Gediminas Castle and Cathedral Square, symbols of the capital. Their combination is also a gateway to the historic centre of the capital. Owing to its uniqueness, the Old Town of Vilnius was inscribed on the UNESCO World Heritage List in 1994