The Kremlin is the official residence of President Vladimir Putin. It's protected by an elite military regiment and has walls up to 21 feet thick - here's a look inside.

Vladimir Gerdo\TASS via Getty Images

The Kremlin is a fortified complex in the heart of Moscow.

• The $4 is a fortified complex in the center of $4, Russia, made up of more than 15 buildings, $4 and more than 1.5 miles of $4
• Since 1991, it's been the official $4, currently $4
• The complex is protected by $4 whose members must be able to hear a whisper from 20 feet away.
• On a recent trip to $4, I visited the Kremlin. I had always imagined the Kremlin being full of administrative buildings, but instead I found beautiful palaces, cathedrals, museums, and gardens.
• $4.

The Moscow Kremlin is a fortified complex in the center of the city made up of $4 that are up to 21 feet thick. It's the $4, although he doesn't actually live there.

While $4 throughout Russia, Moscow's is, by far, the most famous.

On a recent trip to Russia, I paid $10.50 for a ticket to visit a section of the Kremlin. Here's what it looks like inside.