Next to the Colosseum the ruins of a gym have been found, and it is believed to have been used by the gladiators. Opposite the Colosseum is the Colle Oppio, with gardens, terraces and fountains. The agreeable position, the wealth of varieties of flowers (2500 varieties of roses), the imposing character of the ruins of the Baths of Trajan and above all the dramatic background of the Colosseum make this park one of the most inspiring in Rome. From here one can access the Domus Aurea, built by Nero after the burning of the city only to be buried by the construction of the Baths of Trajan, of which together with the foundations of the baths many rooms remain and are interesting for their stupendous murals, plasters and guilt decor. From this splendid residence of the Caesars came many of the sculptural works displayed in the Vatican such as the Laocoonte and the gigantic porphyry cup of one piece which is in the circular room of the Museo Pio Clementino. Entrance to it is on the left of the entrance to the park. The Baths of Trajan were built in A.D. 104 by Apollodoro of Damascus, the same architect who designed Trajan's Forum, and the original plan was a grandiose one which was subsequently the inspiration for the architects of other Roman baths. In fact, the architects of the Baths of Caracalla and the Baths of Diocletian did not vary much from the model of Apollodoro, who thus deserves a pre-eminent position in the history of Roman architecture. Unfortunately, only a few porticos and some ruins of rooms remain of this vast building. Better conserved is a large pool commonly called the Seven Rooms, located just beyond the park in the gardens of Palazzo Brancaccio.