Lida castle was built at first half of 14th century by Duke Gediminas. No one believed that castle could be built on very sandy area, but it happened like that. Lida castle is the biggest structure of such type castles in Belarus (and probably all former Grand Lithuanian Duchy territory) - dimensions are about 80x80 meters. The castle was a part of defensive system of castles in medieval Lithuania. Other famous castles of the same system are in Novogrudok, Krevo, Trakai, Vilnius, Medininkai.
Lida castle is only one castle of such type (rectangular castles), that is almost fully restored. Other rectangular type castles (they are oldest castles in this region) from Grand Lithuanian Duchy are still in ruins (Medininkai and Krevo as an examples).
It is public opinion, that castle was rebuilt not professionally, using too much modern materials. Anyway, nowadays it is one of tourist spot in Belarus.