Nowadays, most of us don't give too much thought to bridges unless we're crossing a particularly high one. But these structures were key to civilization - without them, long distance travel wouldn't have been easy or perhaps even possible. Bridge design, which initially involved using wooden logs to span short distances, has continued to evolve until these structures became true architectural marvels. Here are 8 old bridges in New Mexico that showcase changing engineering techniques. Plus, they're pretty cool to look at!

1. Bridge in the Pecos Wilderness

The grass growing at either end of this bridge near Terrero suggests its days of use are probably over. It spans the Pecos River.

2. Mexican Canyon Bridge, Cloudcroft

This trestle railway bridge in Mexican Canyon is all that remains of the Alamagordo-Sacramento Mountain Railway (once part of the El Paso and Northeastern Railroad). The company built this line to gain access to timber in the Lincoln National Forest, which was needed to continue expanding the country's network of railways.

This photo provides a different perspective of the same bridge.

The train cars that traveled along it transported both freight and passengers.

3. Derelict bridge in the Jarilla Mountains

New Mexico's railroad history means that there are many disused bridges crumbling into disrepair across the state.

4. Bridge near Mogollon

This metal bridge is located off US-180. It has a truss design, which means that

its supports are formed from triangular sections of beam.

5. A Route 66 bridge, near Endee

This portion of Route 66 was in use until 1952. During those years, four beam bridges, like this one, were used to allow the road to sit above the surrounding flood plains.

6. Glen Woody Bridge, near Taos

Whether depicted in color or in black and white, this suspension bridge looks really unsafe.

The Glen Woody Bridge was constructed in 1902 in order to access a mining camp.

7. Percha Creek Bridge, near Hillsboro

This bridge, built in 1927, is on the National Register of Historic Places. Vehicular traffic now crosses the newer bridge, constructed right next to it.

8. Bridge crossing Forgotten Gorge

The bridge appears as neglected as the gorge it spans.

Do you have a soft spot for abandoned structures?

Of course, New Mexico has plenty of bridges that are still in use. The Rio Grande Gorge Bridge, in particular, deserves a spot on everyone's bucket list. But, the next time you spy an old crumbling bridge from your car window, pull over for a moment to admire the incredible progression of these structures throughout time, and to think about all the feats they've made possible.