All the gates are labeled with Roman numerals. Roman numerals appeared 500 years before our era, they were invented by the Etruscans. There is a theory that the Etruscans followed the simplest and at the same time the most ingenious way of creating numbers. They drew from the image of the human hand. For example, 1, 2 and 3 are designated by the number of fingers (I, II, III). And the Roman numeral V depicts an open hand with four fingers pressed together and the thumb set aside. The symbol X represents two crossed arms or a double numeral V.
Roman numerals are written as follows (1 through 12): I, II, III, IV, V, VI, VI, VII, VIII, VIII, IX, X, XI, XII, and so on. The digits I (one), V (five), X (ten) can be used to represent many different numbers.
The Roman number system is a non-position number system in which the value of a digit is clearly defined and does not depend on its position in the number. The letters of the Latin alphabet are used to write numbers: I stands for "one" (1); V stands for "five" (5); X stands for "ten" (10).