In the heart of the American Southwest, Tucson is a vibrant city known for its young, urban crowd, fueled by the University of Arizona. The second largest city in the state, the city has a rich past that's reflected in everything from its historic architecture to its eclectic cultural milieu. Ringed by the rugged peaks of the Santa Rita, Tortolita, Rincon, Tucson and Sierrita Mountains, the city lies in a valley filled with flowering desert cacti that change to pine-trees as the altitude rises. At Sentinel Peak, excavations have revealed signs of settlement as far back as 4,000 years. Hiking and biking are popular activities and draw visitors looking to explore Arizona's natural beauty while enjoying the city's lively vibe.