महाभारतः mahābhārataḥ - book-3, chapter-268, verse-2

रावणश्च विधिं चक्रे लङ्कायां शास्त्रनिर्मितम् ।
प्रकृत्यैव दुराधर्षा दृढप्राकारतोरणा ॥२॥

2. rāvaṇaśca vidhiṁ cakre laṅkāyāṁ śāstranirmitam ,
prakṛtyaiva durādharṣā dṛḍhaprākāratoraṇā.

2. Rāvaṇaḥ ca vidhim cakre Laṅkāyām śāstra-nirmitam
| prakṛtyā eva durādharṣā dṛḍhaprākāratoraṇā

2. And Rāvaṇa established defensive measures in Laṅkā, all crafted according to scriptural injunctions. By its very intrinsic nature (prakṛti), Laṅkā was already unassailable, with formidable walls and strong gateways.

Words meanings summery:

• रावणः (rāvaṇaḥ) - The demon king Rāvaṇa (Rāvaṇa)

• च (ca) - and (and, also)

• विधिम् (vidhim) - (defensive) arrangements or procedures (rule, method, arrangement, procedure)

• चक्रे (cakre) - he established, he implemented (he made, he did, he performed)

• लङ्कायाम् (laṅkāyām) - in the city of Laṅkā (in Laṅkā)

• शास्त्र-निर्मितम् (śāstra-nirmitam) - defensive measures prescribed by military or architectural treatises (made according to scriptures, prescribed by treatises)

• प्रकृत्या (prakṛtyā) - by its inherent nature (prakṛti) (by nature, by intrinsic nature)

• एव (eva) - by its very (nature) (only, indeed, just, very)

• दुराधर्षा (durādharṣā) - (Laṅkā was) naturally unassailable (unassailable, invincible, difficult to attack)

• दृढप्राकारतोरणा (dṛḍhaprākāratoraṇā) - (Laṅkā was) characterized by strong walls and gateways (having strong walls and gates)

Words meanings and morphology

रावणः (rāvaṇaḥ) - The demon king Rāvaṇa (Rāvaṇa)

(proper noun)

Nominative, masculine, singular of Rāvaṇa

Rāvaṇa - Name of the demon king of Laṅkā

च (ca) - and (and, also)

(indeclinable)

विधिम् (vidhim) - (defensive) arrangements or procedures (rule, method, arrangement, procedure)

(noun)

Accusative, masculine, singular of vidhi

vidhi - rule, method, procedure, ordinance

Root: dhā (class 3)

चक्रे (cakre) - he established, he implemented (he made, he did, he performed)

(verb)

3rd person , singular, middle, perfect (liṭ) of kṛ

Perfect tense, 3rd person singular

Irregular perfect formation from root kṛ (Class 8), Middle voice.

Root: kṛ (class 8)

लङ्कायाम् (laṅkāyām) - in the city of Laṅkā (in Laṅkā)

(proper noun)

Locative, feminine, singular of Laṅkā

Laṅkā - Name of the capital city of Rāvaṇa

शास्त्र-निर्मितम् (śāstra-nirmitam) - defensive measures prescribed by military or architectural treatises (made according to scriptures, prescribed by treatises)

(adjective)

Accusative, masculine, singular of śāstra-nirmita

śāstra-nirmita - made according to scriptures/treatises

Compound type : tatpurusha (śāstra+nirmita)

• śāstra – scripture, treatise, rule
  noun (neuter)
  Root: śās (class 2)
• nirmita – made, constructed, created
  past passive participle (masculine)
  Past Passive Participle
  From nir-√mā (to measure, to build)
  Prefix: nir
  Root: mā (class 2)

प्रकृत्या (prakṛtyā) - by its inherent nature (prakṛti) (by nature, by intrinsic nature)

(noun)

Instrumental, feminine, singular of prakṛti

prakṛti - nature, original form, material cause, primal nature (prakṛti)

From pra-√kṛ (to make, do)

Prefix: pra

Root: kṛ (class 8)

एव (eva) - by its very (nature) (only, indeed, just, very)

(indeclinable)

दुराधर्षा (durādharṣā) - (Laṅkā was) naturally unassailable (unassailable, invincible, difficult to attack)

(adjective)

Nominative, feminine, singular of durādharṣa

durādharṣa - unassailable, invincible

From dur- (difficult) + ā-√dhṛṣ (to be bold, attack)

Compound type : prādi-samāsa (dur+ādhṛṣa)

• dur – bad, difficult
  prefix
• ādhṛṣa – attacked, assailed
  past passive participle (feminine)
  Past Passive Participle
  From ā-√dhṛṣ
  Prefix: ā
  Root: dhṛṣ (class 5)

Note: Adjective describing Laṅkā (implied).

दृढप्राकारतोरणा (dṛḍhaprākāratoraṇā) - (Laṅkā was) characterized by strong walls and gateways (having strong walls and gates)

(adjective)

Nominative, feminine, singular of dṛḍhaprākāratoraṇa

dṛḍhaprākāratoraṇa - having strong walls and gates

Compound type : bahuvrīhi (dṛḍha+prākāra+toraṇa)

• dṛḍha – firm, strong, solid
  past passive participle (feminine)
  Past Passive Participle
  From √dṛh (to be firm)
  Root: dṛh (class 1)
• prākāra – wall, rampart, enclosure
  noun (masculine)
  Prefix: pra
  Root: kṛ (class 8)
• toraṇa – gate, arched gateway
  noun (neuter)
  Root: tṝ (class 1)

Note: Adjective describing Laṅkā (implied).