Large Blood Vessels
Both the Aorta and Vena Cava have three layers. Tunicae intima, media, and adventitia.
The Aorta is classified under elastic arteries (conducting arteries). They have (40-70) fenestrated membranes (Concentric layers of elastic membranes) at the tunica media, with smooth muscle cells interspersed between the membranes. Tunica Adventitia consists of thin layer of fibroelastic connective tissue.
The Vena Cava is classified under Large veins. The muscular and elastic layers are not as well developed as compared with Aorta, and the connective tissue components in Vena Cava more pronounced. The Tunica Media consists of connective tissue and smooth muscle cells. Tunica Adventitia have smooth muscle cells oriented in longitudinal bundles, and consists of collagen layers with fibroblasts.
Adapted from: http://myaimst.net/mbbsb12/photo/histo/yr1histo/vessel.html
Micro-photograph taken at AIMST University Anatomy Dissection Hall during Histology class, using Canon A40 camera over light microscope.