Question: The Monument to the Unknown Hero built in 1934-1938 is located in which country and is similar to many other tombs of the unknown soldier?

Context paragraphs:
Tomb of the Unknown Soldier: The Tomb of the Unknown Soldier refers to a monument (cenotaph) in dedication to the services of an unknown soldier and to the common memories of all soldiers killed in any war.  Such tombs can be found in many nations and are usually high-profile national monuments. Throughout history, many soldiers have died in war with their remains being unidentified.  Following World War I, a movement arose to commemorate these soldiers with a single tomb, containing the body of one such unidentified soldier.

The Unknown Warrior: The British tomb of The Unknown Warrior holds an unidentified British soldier killed on a European battlefield during the First World War.  He was buried in Westminster Abbey, London on 11 November 1920, simultaneously with a similar interment of a French unknown soldier at the Arc de Triomphe in France, making both tombs the first to honour the unknown dead of the First World War.  It is the first example of a Tomb of the Unknown Soldier.

The Monument to the Unknown Soldier: The Monument to the Unknown Soldier (Arabic,نصب الجندي المجهول) is a monument in central Baghdad designed by Italian architect Marcello D'Olivo and built between 1979 and 1982.  It is said to be inspired by the glorification of a martyr from the Iran–Iraq War.  In 1986 the national square of Iraq, Great Celebrations square, was built near the monument, and in 1989 the Victory Arches were added to celebrate the victory of the war on Iran.  The Monument represents a traditional shield (dira¹a) dropping from the dying grasp of an Iraqi warrior.  The monument also houses an underground museum.

Firdos Square: Firdos Square (Arabic: ساحة الفردوس‎ , "Sāḥat al-Firdaus " ‎ ) is a public open space in Baghdad, Iraq.  It is named after the Persian word "Firdows", which means "paradise".  The 17 Ramadan Mosque and two of the best-known hotels in Baghdad, the Palestine Hotel and the Sheraton Ishtar, are located on the square.  The roundabout in the center of Firdos Square has been the site of several monuments beginning with the completion of the monumental arch "The Unknown Soldier" in 1959.  It was subsequently replaced by the statue of Saddam Hussein that was torn down by U.S. coalition forces during the invasion of Iraq in 2003.  A green, abstract sculpture by Bassem Hamad al-Dawiri was commissioned to replace the Saddam statue.  In 2009, the architect of the Monument to the Unknown Soldier Rifat Chadirji expressed interest in rebuilding the monument on its original site.  As of 2013, the al-Dawiri statue and the surrounding columns have been removed from Firdos Square.

Tomb of the Unknown Soldier (Warsaw): The Tomb of the Unknown Soldier (Polish: "Grób Nieznanego Żołnierza" ) is a monument in Warsaw, Poland, dedicated to the unknown soldiers who have given their lives for Poland.  It is one of many such national tombs of unknowns that were erected after World War I, and the most important such monument in Poland.

Heikki Savolainen (actor): Heikki Savolainen (9 April 1922 in Pori – 22 January 1975) was a Finnish stage and screen actor renowned for the part of Urho Hietanen in Edvin Laine's 1955 "The Unknown Soldier" (The Unknown Soldier).  He also played several comedic roles in 50's Finnish movies, as well as performing in several radio plays.

Monument to the Unknown Soldier, Sofia: The Monument to the Unknown Soldier (Bulgarian: Паметник на Незнайния воин , "Pametnik na Neznayniya voin") is a monument in the centre of Sofia, the capital of Bulgaria, located just next to the 6th-century Church of St Sophia, on 2 Paris Street.  The monument commemorates the hundreds of thousands of Bulgarian soldiers who died in wars defending their homeland.  Ceremonies involving the President of Bulgaria and foreign state leaders are often performed here.

The Unknown Soldier (1955 film): The Unknown Soldier (Finnish: "Tuntematon sotilas" ) is a Finnish film directed by Edvin Laine and premiered in December 1955.  It is based on "The Unknown Soldier", a novel by Väinö Linna.  The story is about the Continuation War between Finland and the Soviet Union as told from the viewpoint of ordinary Finnish soldiers.  The film was and remains the most successful movie ever in Finland; about 2.8 million people, or more than half the Finnish population, saw it in theaters.  Its portrayal of Linna's characters is widely accepted as canonical.

Tomb of the Unknown Soldier (Romania): The Tomb of the Unknown Soldier (Romanian: "Mormântul Soldatului Necunoscut" ) is a monument located in Bucharest, Romania.  Dedicated to the soldiers who died while fighting for Romania.  It is one of many such national tombs.

Monument to the Unknown Hero: The Monument to the Unknown Hero (Serbian: Споменик Незнаном јунаку / Spomenik Neznanom junaku) is a World War I memorial located atop Mount Avala, south-east of Belgrade, Serbia, and designed by the sculptor Ivan Meštrović.  Memorial was built in 1934-1938 on the place where an unknown Serbian World War I soldier was buried.  It is similar to many other tombs of the unknown soldier built by the allies after the war.  The Žrnov fortress was previously located on the same place.

Supporting paragraphs: Monument to the Unknown Hero Tomb of the Unknown Soldier
Answer: Serbia