Inigo Jones designed the first centrally unsupported one of these structures in England for  the Queen's House, the so-called "Tulip" one.
One of these structures near the Doge's Palace in Venice is flanked by large statues of Mars and Neptune, which is why  it's called the "Giant's" one. Inigo Jones designed the first centrally unsupported one of these structures in England for  the Queen's House, the so-called "Tulip" one. Gaudi placed a lizard fountain in the center of one of these structures in the  (*) Park Guell. Bartolomeo Ammannati carried out plans for one of these structures, made of sandstone, which is three-pronged  and sits in the vestibule below a structure's reading room. For 10 points, name these architectural features, one of which  Michelangelo designed for the Laurentian Library.
One of these structures near the Doge's Palace in Venice is flanked by large statues of Mars and Neptune, which is why  it's called the "Giant's" one.
staircases [accept anything involving stairs or steps]