Stargate.

for the people who do not know of this very well here is a brief video basicly showing the adventures of SG1 the best series

for the people who dont know about stargate here is a breif introduction
A stargate is a massive, circular ring with an inner track of 39 symbols representing star constellations, capable of sending people and objects hundreds of thousands of lightyears via an interstellar conduit called a Wormhole. The Stargate, constructed millenia ago by the Ancients, is made of the alien mineral Naquadah and weighs about 64,000 pounds.
One side of the gate holds nine equally-spaced, V-shaped locking mechanisms, or “chevrons,” capable of locking at least seven constellations in place via a freely-spinning inner track. The first six glyphs lock down a point in space, while the seventh represents the Point of origin. When the seventh chevron locks, an unstable energy vortex emerges from the gate, incinerating everything in its wake. Once the vortex is gone and the event horizon is established, outbound travel may commence.
there are 3 differnt types
the milky way gates
http://www.gateworld.net/wiki/images/thumb/1/1c/Stargate.jpg/300px-Stargate.jpg
the peagasus galaxy gates
http://www.gateworld.net/wiki/images/thumb/c/ce/Atlantisgate.jpg/180px-Atlantisgate.jpg
Perhaps the oldest gates in existence are in the style of the Destiny Stargate
http://www.gateworld.net/wiki/images/thumb/e/e8/Destinygate.jpg/180px-Destinygate.jpg

as always what is a scifi with out some form of space ship, Earth has battle crusers which all look like this

stargate daedalus final mallacore

and fighters which make a f22 look like a bunny
The F302
http://www.gateworld.net/wiki/images/thumb/3/32/F-302.jpg/300px-F-302.jpg

there are other aleins in stargate the Goa’uld a alien reace which takes human hoasts to survive, they try to take over the milky way
A Goa’uld mothership,or a HA’TAK
http://www.gateworld.net/wiki/images/thumb/3/32/Hatak.jpg/300px-Hatak.jpg

there are also other bad guys in this program such as The replicatiors
these are small machines which want to over throw everything even across galaxy’s
http://www.gateworld.net/wiki/images/thumb/b/bd/Replicators.jpg/300px-Replicators.jpg
they are small peices of a jigsaw basicly which can combine to make any shape, and also they can take any technology and turn any metal into themselves

in the second show of stargate there is Stargate : Atlantis which is in short a big, big, big city
http://www.gateworld.net/wiki/images/thumb/8/86/Atlantis.jpg/300px-Atlantis.jpg
it is alien to humans but created by humans pre-evolution, the ancients
The city itself is capable of space flight, and originally resided on the surface of Earth, on the continent that became Antarctica. Between five and 10 million years ago the Ancients left Earth with the great city, bringing it to a planet in the Pegasus Galaxy.
http://www.gateworld.net/wiki/images/thumb/c/c8/Cityship.jpg/300px-Cityship.jpg
yes a city can fly 😀

well thats allot out of my system comment what you think of Stargate 😀

*edit
i did not mention the asgard

One of Earth’s most powerful allies, the ancient and benevolent Asgard were aware of the Tau’ri (Earth) for some time. They assumed the personae of Norse gods on many worlds which fall under their protection.
Physiologically, the Asgard averaged about one meter in height, with grayish skin tones, small, skinny limbs, large heads and black eyes — bearing a striking resemblance to the Roswell Greys described in countless UFO abduction stories. The Asgard were incapable of meiosis (sexual reproduction) for thousands of years. They resorted to a solely enhanced mitosis (cloning) existence, forcing them down a path that eventually led to their extinction. Before that time, some Asgard took drastic steps to ensure the survival of the species, including kidnapping people from Earth to study human development.
http://www.gateworld.net/wiki/images/thumb/0/0b/Asgard.jpg/300px-Asgard.jpg
Despite the Asgard’s small physical stature, their size was no comparison to their intellect. They successfully developed a multitude of advanced technologies that dwarf those of the Goa’uld, including faster-than-light travel that can launch an Asgard vessel from one galaxy to another in minutes.

The ASGARD MOTHERSHIP
http://www.gateworld.net/wiki/images/thumb/e/ec/Asgardmothership.jpg/300px-Asgardmothership.jpg
Feared by Goa’uld across the galaxy, the Asgard mothership is the main arsenal of defense for the Asgard fleet. Incorporating the general shape of Thor’s Hammer at its bow, the Asgard mothership is a relatively flat vessel with two vertical hyperdrive engines at the stern, giving the ship a sleek, streamlined look.

this is relatively basic introduction (yes basic) please look into the story and start with sg1 this is a very good sci-fi