Murano is a group of islands located just north of Venice. It has one of the oldest churches in the Venetian lagoon, the Church of Santa Maria and San Donato. It seems to be little changed since it was last rebuilt sometimes around 1140 and serves as an excellent example of authentic Byzantine style architecture. Behind the altar there is a unique relic: four large bones hanging on the wall. These enormous bones are said to belong to a dragon slain by St. Donato. The impressive, colorful stone mosaic floor in Byzantine style was also made sometimes around 1140. Over the long centuries it has been worn out and seems diminished in effect by superficial repairs, but it has been kept intact to preserve the scars of history. It is the only part of the construction which can be dated more precisely.