Bridges have been around for a very long time. In fact they have been around so long that we don’t even know when they were actually invented. But now before we get started I am going to give you a brief summary of the history of bridges. So in the beginning bridges were really simple structures that people built from things the were really easy to gather- wooden logs, stone and dirt. Because of that, they could only make bridges short and not very long, and their structural smarts were not high because mortar (a paste that people used to put building blocks like stones, bricks, and concrete masonry units together and also fill and seal the irregular gaps between them) was not yet invented and rain slowly but surely made the dirt fillings of the bridge fall apart. Ancient Rome was when the revolution of bridges came into play. Roman engineers found a material the was a lot better to build with. The material was grinded out volcanic rocks and it served as an amazing material for making mortar. This invention allowed them to build much stronger buildings and bridges. After they realized that this was a very useful material Roman architects spread across to Europe, Africa, Asia, building bridges and roads of very high quality. All the way up until the 1700s, bridges were made of timber, stone and masonry. Bridges now a days are currently built out of concrete, fiber reinforced polymers, steel reinforced polymers, stainless steel or all of them mixed together. Living bridges are made of real live plants such as Ficus elastica tree roots in India and wisteria vines in JapanSuspension bridges are a very common and safe way to build a bridge and have became very popular in the last century. Some examples are the Golden Gate Bridge, George Washington Bridge, the Brooklyn Bridge and the Verrazano-Narrows Bridge; these bridges are regular suspension bridges. The Suspension bridge design is where,very large cables are suspended between towers and smaller cables are used to hang the deck of the bridge from the larger cables. They now have a newer and better methods and it is where the cables run directly down from the towers to the roadway. Construction of cable-stayed bridges has proven to not be as expensive as suspension bridges because the materials are cheaper. As a result, Cable-stayed bridges used more than suspension bridges.A truss bridge is a bridge where the superstructure is made of the material called truss (a framework, consisting of rafters, posts, and struts, supporting a roof, bridge, or other architectural things forming big triangles). Truss bridges are the oldest type of what we would consider a modern bridge.Cantilever bridges are built using cantilevers which are beams that are only supported on one end. Cantilever bridges are constructed using a lot of the same styles and materials as beam bridges. The only difference is in the action of the forces through the bridge. Some cantilever bridges are made with extra strength by also having a smaller beam connecting the two cantilevers.Arch bridges have abutments at each end. The of the weight of the bridge is on the sides. The first known arch bridges were built by the Greeks who are famous for their architecture, and include the Arkadiko Bridge. The arch of the Friedensbrücke has the span of 90 m (295 ft) and crosses the valley of the Syrabach River. The difference between the Solkan Bridge and the Friedensbrücke Bridge is that the Solkan Bridge was built from stone blocks, whereas the Friedensbrücke was built from a mixture of crushed stone and cement mortar.Beam bridges are horizontal beams that are supported at both ends by substructure units. The first beam bridges were just very little and simple logs that would sit across streams and simple structures. Now a days beam bridges can vary in sizes from small to medium to large. Beam bridges are typically made of steel, concrete or wood but could be made of other materials. Girder bridges is a type of beam bridge and are usually made of steel as well. Box girder bridges are also made from steel, concrete, or both just like the others.In conclusion there are a lot of different kinds of bridges and they all serve a purpose. Like I said in the in the beginning bridges have been around for a very long time and will most likely stay around forever. Bridges are also getting better and better and are way safer than they might have been 60 years ago. Bridges are also getting even more modern by the day for example the Peace Bridge in Tbilisi, Georgia is one of the most modern looking bridges that I have ever seen in my life. Another example of a modern bridge is The Millau Viaduct in France. But we can also not forget about the classics like the one and only London Bridge and you guessed its in London, England or the Kintaikyo Bridge in Japan. I hope you learned something from this essay.