A question from Yahoo! Answers:

How many Kremlin’s are there in Russia?

Pretty much every Russian city founded before 1500 has or had one. There are three that I know of within 100 miles of Moscow (Moscow, Zaraisk, and Kolomna; the latter survived only partially):

Moscow Kremlin

Zaraisk Kremlin

Kolomna Kremlin

The Serpukhov Kremlin only has two fragments standing:

There used to be kremlins in Vereya, Volokolamsk, Dmitrov, Zvenigorod, Pereyaslavl-Zalessky, and Ruza, but now only their bulwarks remain. Again, this is only within 100 miles of Moscow.

The Kremlin page on Russian Wikipedia lists 20 known locations for stone-built kremlins, 10 for kremlins built of stone and wood, and 37 for wooden kremlins.

All images courtesy of Wikipedia.