Cossack Squats (also called Skandasana in yoga) are a great way to strengthen the legs while mobilizing the hips. You'll get a great stretch for the adductors (inner thigh) and a deep burn in the glutes and quads.

Tutorial (1-10 min)

Beginner

Squat / Lunge

Yoga Calisthenics

Lower Body
Hips Adductors
Quads