Attention is drawn to the fact that the borders of majority of protected old towns in Lithuania are juridical rather than structural. This complicates protection of these territories. The following concepts are defined: historic town, old town, historic kernel of town, historic suburb. Urban characteristics (plan, buildup, size-and-space composition) of the historic suburbs of Vilnius, Kaunas, Klaipeda and Kedainiai that are within the borders of the old towns are described in a summarized way. The components of the old towns (historic town's kernel and historic suburbs) are distinguished in the illustrating material.