An episode that uses the bad plot device of a twin of Earth with an alternate history
With the entire galaxy to choose from and all the possible scenarios of planet structure and cultural development, it was unfortunate that the producers of Star Trek had to use Earth as a model. In several episodes, and this is one of them, Earth history was used as the model for the development of a culture.
In this case the Enterprise is investigating the disappearance six years ago of the SS Beagle. Approaching the planet of the disappearance, the Enterprise picks up the television broadcast of a gladiatorial contest where one of the members of the Beagle crew is killed. Kirk, Spock and McCoy beam down and make contact with some runaway slaves who, oddly enough worship the sun. They learn that Captain Merrick of the Beagle is now Merrickus, the lord of the gladiatorial games.
The landing party and a slave Maximus are captured outside the city and taken in front of Merrick and Proconsul Claudius. Kirk quickly realizes that this is a parallel Earth where Rome never fell. Although mid-twentieth century technology has been developed, the Roman gladiatorial contests and the social structure of slavery remain intact. Claudius convinced Merrick to beam his men down to be killed in order to keep their civilization from being altered. Kirk is then told to order the members of his crew to beam down. When he refuses, he is given a ringside seat for Spock and McCoy fighting to the death in the arena. Spock easily defeats his opponent, but when he aids McCoy, a foul is declared.
Claudius shows his respect for Kirk as a commander and on the night before his execution, he sends one of his loveliest female slaves to spend the night with him. Fortunately, at the time when Kirk is to be executed, Scotty disrupts the power system and he is able to get away and free Spock and McCoy. Merrick has taken one of the communicators and in his last act before saving the Enterprise landing party, he contacts the Enterprise to beam them up.
While there are some good moments in this episode, overall the reliance on a twin Earth with an alternate history makes for a poor plot and episode. The best moment is the meeting between Kirk and Claudius when Kirk asks him why he was given the slave for the evening. Claudius, Kirk's enemy, orders his death, yet still respects him as an opponent and fellow leader.

Rome, Rome, Rome your boat
First off, make no mistake that this is a show about ancient Rome, 60s TV, and (what is unique for Trek) a mildly pro-Christian message.

In short, Kirk, Spock, and McCoy visit a planet that is essentially 1960's Earth (there's that implausible parallel-evolution premise again) except that Rome never fell. The reason Rome never fell, as it turned out, is that Jesus was born 2,000 years later or for some reason the message of the "Son worshippers" (believed at first to be "sun worshippers") never got out until recently. And Rome not falling turns out to be a bad, bad thing.

Probably the best thing about this episode is the use of televised gladitorial games to satirize 1960's TV and Nielsen ratings, which if you'll recall, classic Trek struggled so much with. This episode has one of the best lines of the entire series: "If you lower our ratings, Flavius, we'll do a special on you!"

Another thing notable about the show is that the evil Proconsul admires Kirk and so wants to give him a gift before killing him... a night with the Proconsul's lovely blonde slave girl. The scene is one of Kirk's better love scenes. However, the sexism in the writing becomes clear in a line of dialogue in a subsequent scene. Kirk says (about the previous night): "They threw me a few curves." This is the sort of non-PC writing that, for better or worse, we were never to see in TNG etc.

Best of Sci-Fi
I am a very big Star Trek fan, especially the original series. I haven't seen too many of them that I didn't care for. Bread and Circuses wasn't one of the scientific episodes, but deals more with barbarians from a different world.
kirk, Spock, and Mcoy beams down to a planet in search of a crew who had disappeared years earlier. Getting, there, they find the captain of the missing crew has joined with the barbarians of this planet who love to have arena fights til the death.
Kirk is faced with the decision of watching Mcoy and Spock die in the arena, or call the rest of his crew down to face the arena.
The best part of this movie, is Spock and Mcoy's conversation while they are in their cell. It shows how Spock and Mcoy feels about each other and it's an excellent dialogue and makes the show definetly worth seeing.

ATOZ, in his youth
The Roman episode was the first in a slew of parallel earth episodes, and was one of the better ones. The episode features a lot of action and a number of exterior shots. There is also much violence, and some of it is fairly chilling. While there is some editiorializing on 1) our society's bloodlust this is in my opinion negated by the Pro-Christian bias (I don't have anything against Christianity-I just prefer religion to be dealt with more subjectively on Trek).

For better or worse, the show was becoming less introspective. An argument could be made that some of these episodes should have been reigned in a bit. But Star Trek was riding high at this point on a string of strong stories and fun episodes; few could have guessed that the quality would start to deteriorate in just a few episodes.

Tidbit: This episode and Elaan of Troyius were the two that took the longest to get from production to the TV screen. In Elaan of Troyius I always assumed the delay was due to the spacecraft special effects. What was the explanation here?

'Prophesy of the future?'
'Bread and Circuses',hmmm? When I saw this episode I thought the worshippers of the 'sun' were christians,but when I became older,I later interpreted the worshippers of the 'sun' as worshippers of Japan. the 'fish'(Peter the fisherman) has been the sign of christians and never the 'sun',but for Japan the standard of the 'sun'(Land of the rising sun) has been the national standard and flag of Japan. A lot of are architecture,religion,and ideals are rooted from ancient Rome. For instance like 'football'(resemble Gladitorial games),months of the year 'July' (Julius Caesar),'August' (Augustus Caesar),the United States 'Senate'(Roman Senate),and the architecture resembles that of ancient Rome. I would also like to state that Julius Caesar conquered the island of Britain,and later Britain conquered America which makes America also Roman,not to mention you have a 'Pontiff' in Rome like the ancient days. Is the Roman Empire really dead? Do the answers of the future come from Japan,the 'land of the rising sun'. Lots of people called Marcellus,Marcus,Antonius(Anthony),Augustus(Gus),and Octavia(female). Like a Richard Wagner opera,'Star Trek' opens up the imagination and intellect. Have fun,that's the idea.