.wrap {
    background-color: black;
    text-align:center;
    position: relative;
    -moz-border-radius: 50%;
    -webkit-border-radius: 50%;
    border-radius: 50%;
    display: inline-block;
}
.wrap:hover .text_over_image {
    display: block;
}
.wrap:hover img {
    opacity: 0.5;
}
.text_over_image {
    position: absolute;
    display: none;
    margin: auto;
    top: 0;
    left:0;
    right:0;
    bottom:0;
    color:#fff;
    line-height:210px;
    vertical-align:middle;
}