<svg xmlns='http://www.w3.org/2000/svg'>
<g transform="translate(30,30)">
  <!-- transform-origin specifies a point in user space -->
  <rect x='10' y='10' width='100' height='100' fill='blue' stroke-width='20' stroke='black'
        style="transform:rotate(90deg); transform-origin:10px 110px;"/>
</g>
</svg>