Mars (also known as the Red Planet, Sol IV or Sol Secundus) was once a cool Ae-Class world but was terraformed into a temperate Me-Class world. It is the most Earthlike world in the Sol System aside from Earth.
Due to it's cultural significance throughout Human history, Mars is considered to be one of the most important and famous worlds throughout the entire human race, and its colonization is often considered the true beginning of the rise of humanity into the greater galactic and universal stage.
Due to its distance from Sol, most of the climates are cooler than their Earth counterparts. The four major volcanoes on the planet jut out of the atmosphere entirely. Many of the major cities on Mars exist in some of the larger craters near the local atmospheric datum. Each city has its own local weather.
At higher elevations, the terrain resembles terrestrial alpine biomes and the Hellas Sea resembled the Mediterranean Sea. The poles are larger than their earth counterparts and the winds on the planet are much more predictable than their Earth counterparts.
Mars has a population of just over 2 trillion spread across the cool tundras, forests, deserts, and cities. Thanks to the low gravity, Martians are taller and weaker than terrestrial humans.
Mars is the second oldest human colonized world and second most diverse culturally as nearly every country sent colonists to Mars, even religious groups that lived in the higher elevations moved and built monasteries and temples in the now snow covered higher elevations.
Many groups who’d grown up near the Mediterranean moved to the new Hellas Sea where they set up many small fishing cities
The native human Martian population is split into two groups. Since the gravitational pull of Mars is similar to that of Mercury, half of the population have since genetically engineered themselves to be able to fly using wings. They refer to themselves as Aerians. The non-winged inhabitants of the planet simply refer to themselves as Martians. This has caused a genetic shift over the millennia since the colonization of the planet, so much so that interbreeding is not naturally possible with Aerians and Martians.
Like with most worlds, Mars does not possess one singular culture, but hundreds which have evolved over the millennia. There is no one singular unified aspect to Martian culture. Mars is a world which values scientific advancement and the research that goes into scientific theory and application. It has been home to a great number of scientists and researchers for millennia, and is considered to be something of the scientific capital of the Sol system. Hundreds of different scientific advancements have come from the world, and have been used to contribute to the character of Humanity as a whole.
Mars' architecture in particular is of note, due to it's immense variety because of it's many stages of development during terraforming. The remnants of caverns and underground cities are scattered all over MArs, and are till used to this day for various purposes. Many domed cities scatter the Martian surface from the earliest days of colonization, when the temperature was still in need of heating up, which many still reside in.
Outside of these, the Martian architecture in general seems remnant of the Roman empire and the Aztec empire from ancient Earth - Huge flat-topped pyramids and painstakingly beautiful carved statues are found all over Mars.
Mars formed like most planets in the Sol System, where gravity pulled swirling gas and dust together and formed the planet.
In its early history, Mars had a thicker carbon dioxide atmosphere as well as shallow water oceans. Primitive life evolved in these oceans but as Mars' atmosphere was stripped away by solar winds, the environment cooled and eventually all life on Mars went extinct.
The first humans to step foot on Mars did so on March 23, 2061 near Valles Marineris. After four missions, the last one leaving Mars on July 4, 2070, Earth began sending out reusable rockets full of compressed chlorofluorocarbons towards Mars. Their payload was launched into the Martian atmosphere and crashed landed on the surface. This caused the compressed gasses to be ejected into the atmosphere. For fifty years, the rockets kept bombarding the surface with massive containers of CFCs. This caused a global rise in temperature, causing gasses trapped in the frozen wastelands to be released into the atmosphere as well as massive flooding as subsurface water melted.By the 2120s, driver probes were being regularly sent to the asteroid belt and diverted many ice asteroids into the Martian orbit and skimming them across the Martian atmosphere.
Due to the lack of a native magnetic field, one had to be artificially constructed around Mars' L1 Lagrange point to protect the planet from solar radiation. This was accomplished by the construction of around three inflatable structures, each of which generated a magnetic dipole of around 2 tesla. The structures were built in 2301 and placed in orbit two years later.
While diverting asteroids, one probe discovered an iron rich dwarf planet within the asteroid belt. Scientists on Earth debated moving this world into Martian orbit to keep future inhabitants of the terraformed world safe from solar radiation. Simud, as the world is now called, was eventually moved into orbit in 3021.
With the ever thickening atmosphere, life had to be introduced and the first microorganisms sent to Mars were deployed in 2431. These had been engineered to digest carbon dioxide and expelled oxygen. At the same time, nitrogen was extracted from mineral deposits on Mars by nanotech, these deposits having been discovered centuries before by the Curiosity rover. Another source of nitrogen came from mining the atmosphere of Titan. The next wave of imported life was a form of lichen which had been engineered to eat away at the Martian dust and form soil with which new plants could be planted.
By the year 2700, the colonists could leave their homes if they were wearing masks since the mean average temperature on the planet had risen to around -3.4°C
With the introduction of Simud in 3021, Mars' terraforming was reaching completion. Eventually, the planet was habitable for human colonization in 3258.
The three artificial Lagrange Magnetic Fields remained in place around Mars for millennia until the year 12012 when the means of artificially restarting a planetary magnetic field was discovered. Upon the restarting of Mars' core, the four formerly extinct volcano's on Mars erupted in a magnificent display of raw power and added to the already massive height with large lava flows. Since that time, the volcanoes erupted every few hundred years or so before once again becoming extinct.