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.

The Kremlin is a fortified complex in the center of Moscow, Russia.

It's the official residence of the Russian president, Vladimir Putin.

The complex spans about 68 acres and includes at least 15 buildings, 20 towers, and gardens.

In some places, the walls are up to 21 feet thick.

Although the Kremlin is the president's official residence, Putin doesn't actually live there.

Whereas the US president lives in the White House, the president of Russia doesn't live at the Kremlin.

Instead, Putin's Moscow home is the Novo-Ogoryevo residence, tucked away behind high walls patrolled by guards in a ritzy suburb west of the city.

The Kremlin is protected by an elite military regiment known as the Presidential Regiment.

Getting accepted into the Presidential Regiment is no easy task.

According to Russian newspaper Russia Beyond, applicants must adhere to certain BMI standards, measure between 5 feet 7 inches and 6 feet 2 inches, and be able to hear a whisper from nearly 20 feet away.

On a trip to Russia in June, I went to go check out the Moscow Kremlin.

The ticket office is just outside the Kremlin's walls near the Trinity Tower entrance.

Although the president's residence and the Kremlin's administrative buildings are closed to the public, visitors can buy tickets to the complex's museums, historical buildings, and churches.

After waiting in line for less than 10 minutes, I had my ticket. I bought a ticket to the Architectural complex of the Cathedral Square section of the Kremlin, which cost 700 rubles, or about $10.50.

There are five different sections of the Kremlin for which you can buy tickets:

1. The Armoury Chamber, for 1,000 rubles or about $15, which gives access to a museum that displays items such as ancient state regalia, ceremonial royal garments, collections of Russian-made gold- and silverware, and ceremonial arms and armor.

2. The Architectural complex of the Cathedral Square, which costs 700 rubles, or about $10.50.

3. The Temporary Exhibitions, for 500 rubles, about $7.50.

4. New Kremlin Square, for 250 rubles, about $3.75.

5. Ivan the Great Bell-Tower Complex, for 350 rubles, about $5.25.

I chose the second ticket, the Architectural complex of the Cathedral Square, after reading numerous reviews that called it the most beautiful and interesting part of the Kremlin.

I had to wait in line for about 25 minutes to pass through a security check before entering the Kremlin.

The security check consisted of putting my bag through a conveyor belt scanner and then walking through a full-body scanner.

After the security check, I followed other tourists up a pathway and passed inside the Kremlin's walls through the Trinity Tower.

The Kremlin's walls are punctuated by 20 defensive towers of varying sizes that were built between 1485 and 1495. Each tower has a name.

After passing through the tower, the first building I saw was the ominous and very Soviet-looking State Kremlin Palace.

Built in 1961, the palace is the newest building in the Kremlin complex.

It was constructed to hold state events and meetings of the Communist Party of the Soviet Union, but today, it serves as a concert and theater venue.

A large portion of the building is reportedly built up to 50 feet underground.

In the heart of the Kremlin complex is the area known as Cathedral Square.

Cathedral Square includes the Assumption, Archangel, and Annunciation cathedrals, the Church of Laying Our Lady's Holy Robe, the Patriarch's Palace with the Twelve Apostles' Church, and the Ivan the Great Bell Tower complex, as well as exhibition halls in the Assumption Belfry and the One-Pillar Chamber of the Patriarch's Palace.

Before my trip to Russia, I knew very little about the Kremlin, but I had always thought it would be made up of imposing, Soviet-style government buildings, much like the State Kremlin Palace.

But the relatively newly built State Kremlin Palace is clearly an architectural anomaly in the Kremlin rather than the norm.

The Assumption Cathedral is known as the religious center of Moscow.

It has held coronations of tsars and emperors and church services for successful military campaigns.

The Ivan the Great Bell Tower Complex took three centuries to build.

Inside is a museum that chronicles the history of the Kremlin's construction.

Unfortunately, it was closed at the time of my visit, so I couldn't get a look inside.

I spent about an hour wandering in and out of various cathedrals and museums in Cathedral Square.

The Archangel Cathedral is the burial place of many Russian grand princes and tsars, while the Annunciation Cathedral served as their private chapel.

I spotted several tour groups making their way around Cathedral Square, but the size of the area meant that it wasn't too crowded outside.

Inside the cathedrals, on the other hand, were swarms of people, so I didn't linger.

From Cathedral Square, I wandered over to the Alexander Garden, which was filled with colorful flower beds, tall leafy trees, and manicured grass.

The Alexander Garden is the oldest public park in Moscow.

Part of the garden was blocked off by guards and I heard a helicopter landing behind it.

According to the Moscow Times, the president had a helicopter landing pad built at the Kremlin in 2013 after complaints of his motorcade creating traffic jams in Moscow when he'd go back and forth from his suburban residence.

Diagonal from the gardens is the Kremlin Senate, where a fleet of black government cars with blue lights on the roof were parked.

The Kremlin Senate was used by the Soviet government for meetings of the USSR Council of Ministers.

Since 1991, the building has been the official residence of the Russian president. It's closed to the public.

I exited the Kremlin through the Spasskaya Tower on the eastern wall, which leads out to Red Square.

I didn't feel like I'd missed out by skipping the Armoury Chamber or the Temporary Exhibitions, but for travelers who are very interested in museums or particularly interested in Russian history, they might be a worthy addition.

At $10.50, visiting the Kremlin was one of the more affordable tourist attractions I've been to in a major city, and in my opinion, it rivaled Moscow's top tourist attraction, Red Square. But while I'd seen Red Square plastered all over Instagram before seeing it in person, the Kremlin was both less crowded and completely new to my eyes.